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PM: rework signal handling

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- introduce PROC_STOPPED flag, which tracks whether the process is
  stopped on PROC_STOP in the kernel, rather than implicitly deriving
  this from PM_SIG_PENDING;
- make the process resumption test based on current state rather than
  state transitions;
- add and clarify several flag checks in the signal handling code;
- add test79 to test signal handling robustness.

Change-Id: Ic8c7527095035b300b56f2ab1b9dd190bd4bf001
This commit is contained in:
David van Moolenbroek 2013-10-27 13:47:45 +01:00 committed by Lionel Sambuc
parent 4d4e70daaa
commit 595d73a896
12 changed files with 715 additions and 114 deletions
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1
distrib/sets/lists/minix/mi
View file

@ -5800,6 +5800,7 @@
./usr/tests/minix-posix/test76 minix-sys ./usr/tests/minix-posix/test76 minix-sys
./usr/tests/minix-posix/test77 minix-sys ./usr/tests/minix-posix/test77 minix-sys
./usr/tests/minix-posix/test78 minix-sys ./usr/tests/minix-posix/test78 minix-sys
./usr/tests/minix-posix/test79 minix-sys
./usr/tests/minix-posix/test8 minix-sys ./usr/tests/minix-posix/test8 minix-sys
./usr/tests/minix-posix/test9 minix-sys ./usr/tests/minix-posix/test9 minix-sys
./usr/tests/minix-posix/testinterp minix-sys ./usr/tests/minix-posix/testinterp minix-sys

4
servers/is/dmp_pm.c
View file

@ -25,11 +25,11 @@ static char *flags_str(int flags)
str[1] = (flags & ZOMBIE) ? 'Z' : '-'; str[1] = (flags & ZOMBIE) ? 'Z' : '-';
str[2] = (flags & ALARM_ON) ? 'A' : '-'; str[2] = (flags & ALARM_ON) ? 'A' : '-';
str[3] = (flags & EXITING) ? 'E' : '-'; str[3] = (flags & EXITING) ? 'E' : '-';
str[4] = (flags & STOPPED) ? 'S' : '-'; str[4] = (flags & TRACE_STOPPED) ? 'T' : '-';
str[5] = (flags & SIGSUSPENDED) ? 'U' : '-'; str[5] = (flags & SIGSUSPENDED) ? 'U' : '-';
str[6] = (flags & REPLY) ? 'R' : '-'; str[6] = (flags & REPLY) ? 'R' : '-';
str[7] = (flags & VFS_CALL) ? 'F' : '-'; str[7] = (flags & VFS_CALL) ? 'F' : '-';
str[8] = (flags & PM_SIG_PENDING) ? 's' : '-'; str[8] = (flags & PROC_STOPPED) ? 's' : '-';
str[9] = (flags & PRIV_PROC) ? 'p' : '-'; str[9] = (flags & PRIV_PROC) ? 'p' : '-';
str[10] = (flags & PARTIAL_EXEC) ? 'x' : '-'; str[10] = (flags & PARTIAL_EXEC) ? 'x' : '-';
str[11] = (flags & DELAY_CALL) ? 'd' : '-'; str[11] = (flags & DELAY_CALL) ? 'd' : '-';

15
servers/pm/forkexit.c
View file

@ -296,8 +296,15 @@ int dump_core; /* flag indicating whether to dump core */
* This order is important so that VFS can tell drivers to cancel requests * This order is important so that VFS can tell drivers to cancel requests
* such as copying to/ from the exiting process, before it is gone. * such as copying to/ from the exiting process, before it is gone.
*/ */
if ((r = sys_stop(proc_nr_e)) != OK) /* stop the process */ /* If the process is not yet stopped, we force a stop here. This means that
panic("sys_stop failed: %d", r); * the process may still have a delay call pending. For this reason, the main
* message loop discards requests from exiting processes.
*/
if (!(rmp->mp_flags & PROC_STOPPED)) {
if ((r = sys_stop(proc_nr_e)) != OK) /* stop the process */
panic("sys_stop failed: %d", r);
rmp->mp_flags |= PROC_STOPPED;
}
if((r=vm_willexit(proc_nr_e)) != OK) { if((r=vm_willexit(proc_nr_e)) != OK) {
panic("exit_proc: vm_willexit failed: %d", r); panic("exit_proc: vm_willexit failed: %d", r);
@ -337,7 +344,7 @@ int dump_core; /* flag indicating whether to dump core */
/* Clean up most of the flags describing the process's state before the exit, /* Clean up most of the flags describing the process's state before the exit,
* and mark it as exiting. * and mark it as exiting.
*/ */
rmp->mp_flags &= (IN_USE|VFS_CALL|PRIV_PROC|TRACE_EXIT); rmp->mp_flags &= (IN_USE|VFS_CALL|PRIV_PROC|TRACE_EXIT|PROC_STOPPED);
rmp->mp_flags |= EXITING; rmp->mp_flags |= EXITING;
/* Keep the process around until VFS is finished with it. */ /* Keep the process around until VFS is finished with it. */
@ -475,7 +482,7 @@ int do_waitpid()
check_parent(rp, TRUE /*try_cleanup*/); check_parent(rp, TRUE /*try_cleanup*/);
return(SUSPEND); return(SUSPEND);
} }
if (rp->mp_flags & STOPPED) { if (rp->mp_flags & TRACE_STOPPED) {
/* This child meets the pid test and is being traced. /* This child meets the pid test and is being traced.
* Deliver a signal to the tracer, if any. * Deliver a signal to the tracer, if any.
*/ */

6
servers/pm/main.c
View file

@ -26,6 +26,7 @@
#include <string.h> #include <string.h>
#include <machine/archtypes.h> #include <machine/archtypes.h>
#include <env.h> #include <env.h>
#include <assert.h>
#include "mproc.h" #include "mproc.h"
#include "param.h" #include "param.h"
@ -484,6 +485,11 @@ static void handle_vfs_reply()
break; break;
case PM_UNPAUSE_REPLY: case PM_UNPAUSE_REPLY:
/* The target process must always be stopped while unpausing; otherwise
* it could just end up pausing itself on a new call afterwards.
*/
assert(rmp->mp_flags & PROC_STOPPED);
/* Process is now unpaused */ /* Process is now unpaused */
rmp->mp_flags |= UNPAUSED; rmp->mp_flags |= UNPAUSED;

6
servers/pm/mproc.h
View file

@ -76,15 +76,15 @@ EXTERN struct mproc {
#define IN_USE 0x00001 /* set when 'mproc' slot in use */ #define IN_USE 0x00001 /* set when 'mproc' slot in use */
#define WAITING 0x00002 /* set by WAIT system call */ #define WAITING 0x00002 /* set by WAIT system call */
#define ZOMBIE 0x00004 /* waiting for parent to issue WAIT call */ #define ZOMBIE 0x00004 /* waiting for parent to issue WAIT call */
#define PROC_STOPPED 0x00008 /* process is stopped in the kernel */
#define ALARM_ON 0x00010 /* set when SIGALRM timer started */ #define ALARM_ON 0x00010 /* set when SIGALRM timer started */
#define EXITING 0x00020 /* set by EXIT, process is now exiting */ #define EXITING 0x00020 /* set by EXIT, process is now exiting */
#define TOLD_PARENT 0x00040 /* parent wait() completed, ZOMBIE off */ #define TOLD_PARENT 0x00040 /* parent wait() completed, ZOMBIE off */
#define STOPPED 0x00080 /* set if process stopped for tracing */ #define TRACE_STOPPED 0x00080 /* set if process stopped for tracing */
#define SIGSUSPENDED 0x00100 /* set by SIGSUSPEND system call */ #define SIGSUSPENDED 0x00100 /* set by SIGSUSPEND system call */
#define REPLY 0x00200 /* set if a reply message is pending */ #define REPLY 0x00200 /* set if a reply message is pending */
#define VFS_CALL 0x00400 /* set if waiting for VFS (normal calls) */ #define VFS_CALL 0x00400 /* set if waiting for VFS (normal calls) */
#define PM_SIG_PENDING 0x00800 /* process got a signal while waiting for VFS */ #define UNPAUSED 0x01000 /* VFS has replied to unpause request */
#define UNPAUSED 0x01000 /* process is not in a blocking call */
#define PRIV_PROC 0x02000 /* system process, special privileges */ #define PRIV_PROC 0x02000 /* system process, special privileges */
#define PARTIAL_EXEC 0x04000 /* process got a new map but no content */ #define PARTIAL_EXEC 0x04000 /* process got a new map but no content */
#define TRACE_EXIT 0x08000 /* tracer is forcing this process to exit */ #define TRACE_EXIT 0x08000 /* tracer is forcing this process to exit */

2
servers/pm/proto.h
View file

@ -87,7 +87,7 @@ int do_settime(void);
/* trace.c */ /* trace.c */
int do_trace(void); int do_trace(void);
void stop_proc(struct mproc *rmp, int sig_nr); void trace_stop(struct mproc *rmp, int sig_nr);
/* utility.c */ /* utility.c */
pid_t get_free_pid(void); pid_t get_free_pid(void);

279
servers/pm/signal.c
View file

@ -28,22 +28,25 @@
#include <signal.h> #include <signal.h>
#include <sys/resource.h> #include <sys/resource.h>
#include <string.h> #include <string.h>
#include <assert.h>
#include "mproc.h" #include "mproc.h"
#include "param.h" #include "param.h"
static void unpause(struct mproc *rmp); static int unpause(struct mproc *rmp);
static int sig_send(struct mproc *rmp, int signo); static int sig_send(struct mproc *rmp, int signo);
static void sig_proc_exit(struct mproc *rmp, int signo); static void sig_proc_exit(struct mproc *rmp, int signo);
/*===========================================================================* /*===========================================================================*
* do_sigaction * * do_sigaction *
*===========================================================================*/ *===========================================================================*/
int do_sigaction() int do_sigaction(void)
{ {
int r; int r;
struct sigaction svec; struct sigaction svec;
struct sigaction *svp; struct sigaction *svp;
assert(!(mp->mp_flags & (PROC_STOPPED | VFS_CALL | UNPAUSED)));
if (m_in.sig_nr == SIGKILL) return(OK); if (m_in.sig_nr == SIGKILL) return(OK);
if (m_in.sig_nr < 1 || m_in.sig_nr >= _NSIG) return(EINVAL); if (m_in.sig_nr < 1 || m_in.sig_nr >= _NSIG) return(EINVAL);
@ -86,8 +89,10 @@ int do_sigaction()
/*===========================================================================* /*===========================================================================*
* do_sigpending * * do_sigpending *
*===========================================================================*/ *===========================================================================*/
int do_sigpending() int do_sigpending(void)
{ {
assert(!(mp->mp_flags & (PROC_STOPPED | VFS_CALL | UNPAUSED)));
mp->mp_reply.reply_mask = (long) mp->mp_sigpending; mp->mp_reply.reply_mask = (long) mp->mp_sigpending;
return OK; return OK;
} }
@ -95,7 +100,7 @@ int do_sigpending()
/*===========================================================================* /*===========================================================================*
* do_sigprocmask * * do_sigprocmask *
*===========================================================================*/ *===========================================================================*/
int do_sigprocmask() int do_sigprocmask(void)
{ {
/* Note that the library interface passes the actual mask in sigmask_set, /* Note that the library interface passes the actual mask in sigmask_set,
* not a pointer to the mask, in order to save a copy. Similarly, * not a pointer to the mask, in order to save a copy. Similarly,
@ -107,9 +112,10 @@ int do_sigprocmask()
* *
* KILL and STOP can't be masked. * KILL and STOP can't be masked.
*/ */
int i; int i;
assert(!(mp->mp_flags & (PROC_STOPPED | VFS_CALL | UNPAUSED)));
mp->mp_reply.reply_mask = (long) mp->mp_sigmask; mp->mp_reply.reply_mask = (long) mp->mp_sigmask;
switch (m_in.sig_how) { switch (m_in.sig_how) {
@ -150,8 +156,10 @@ int do_sigprocmask()
/*===========================================================================* /*===========================================================================*
* do_sigsuspend * * do_sigsuspend *
*===========================================================================*/ *===========================================================================*/
int do_sigsuspend() int do_sigsuspend(void)
{ {
assert(!(mp->mp_flags & (PROC_STOPPED | VFS_CALL | UNPAUSED)));
mp->mp_sigmask2 = mp->mp_sigmask; /* save the old mask */ mp->mp_sigmask2 = mp->mp_sigmask; /* save the old mask */
mp->mp_sigmask = (sigset_t) m_in.sig_set; mp->mp_sigmask = (sigset_t) m_in.sig_set;
sigdelset(&mp->mp_sigmask, SIGKILL); sigdelset(&mp->mp_sigmask, SIGKILL);
@ -164,14 +172,15 @@ int do_sigsuspend()
/*===========================================================================* /*===========================================================================*
* do_sigreturn * * do_sigreturn *
*===========================================================================*/ *===========================================================================*/
int do_sigreturn() int do_sigreturn(void)
{ {
/* A user signal handler is done. Restore context and check for /* A user signal handler is done. Restore context and check for
* pending unblocked signals. * pending unblocked signals.
*/ */
int r; int r;
assert(!(mp->mp_flags & (PROC_STOPPED | VFS_CALL | UNPAUSED)));
mp->mp_sigmask = (sigset_t) m_in.sig_set; mp->mp_sigmask = (sigset_t) m_in.sig_set;
sigdelset(&mp->mp_sigmask, SIGKILL); sigdelset(&mp->mp_sigmask, SIGKILL);
sigdelset(&mp->mp_sigmask, SIGSTOP); sigdelset(&mp->mp_sigmask, SIGSTOP);
@ -184,7 +193,7 @@ int do_sigreturn()
/*===========================================================================* /*===========================================================================*
* do_kill * * do_kill *
*===========================================================================*/ *===========================================================================*/
int do_kill() int do_kill(void)
{ {
/* Perform the kill(pid, signo) system call. */ /* Perform the kill(pid, signo) system call. */
@ -194,7 +203,7 @@ int do_kill()
/*===========================================================================* /*===========================================================================*
* do_srv_kill * * do_srv_kill *
*===========================================================================*/ *===========================================================================*/
int do_srv_kill() int do_srv_kill(void)
{ {
/* Perform the srv_kill(pid, signo) system call. */ /* Perform the srv_kill(pid, signo) system call. */
@ -209,6 +218,72 @@ int do_srv_kill()
return check_sig(m_in.pid, m_in.sig_nr, TRUE /* ksig */); return check_sig(m_in.pid, m_in.sig_nr, TRUE /* ksig */);
} }
/*===========================================================================*
* stop_proc *
*===========================================================================*/
static int stop_proc(struct mproc *rmp, int may_delay)
{
/* Try to stop the given process in the kernel. If successful, mark the process
* as stopped and return TRUE. If the process is still busy sending a message,
* the behavior depends on the 'may_delay' parameter. If set, the process will
* be marked as having a delay call pending, and the function returns FALSE. If
* not set, the caller already knows that the process has no delay call, and PM
* will panic.
*/
int r;
assert(!(rmp->mp_flags & (PROC_STOPPED | DELAY_CALL | UNPAUSED)));
r = sys_delay_stop(rmp->mp_endpoint);
/* If the process is still busy sending a message, the kernel will give us
* EBUSY now and send a SIGSNDELAY to the process as soon as sending is done.
*/
switch (r) {
case OK:
rmp->mp_flags |= PROC_STOPPED;
return TRUE;
case EBUSY:
if (!may_delay)
panic("stop_proc: unexpected delay call");
rmp->mp_flags |= DELAY_CALL;
return FALSE;
default:
panic("sys_delay_stop failed: %d", r);
}
}
/*===========================================================================*
* try_resume_proc *
*===========================================================================*/
static void try_resume_proc(struct mproc *rmp)
{
/* Resume the given process if possible. */
int r;
assert(rmp->mp_flags & PROC_STOPPED);
/* If the process is blocked on a VFS call, do not resume it now. Most likely * it will be unpausing, in which case the process must remain stopped.
* Otherwise, it will still be resumed once the VFS call returns. If the
* process has died, do not resume it either.
*/
if (rmp->mp_flags & (VFS_CALL | EXITING))
return;
if ((r = sys_resume(rmp->mp_endpoint)) != OK)
panic("sys_resume failed: %d", r);
/* Also unset the unpaused flag. We can safely assume that a stopped process
* need only be unpaused once, but once it is resumed, all bets are off.
*/
rmp->mp_flags &= ~(PROC_STOPPED | UNPAUSED);
}
/*===========================================================================* /*===========================================================================*
* process_ksig * * process_ksig *
*===========================================================================*/ *===========================================================================*/
@ -261,23 +336,30 @@ int process_ksig(endpoint_t proc_nr_e, int signo)
* signal settings. The process may also have forked, exited etcetera. * signal settings. The process may also have forked, exited etcetera.
*/ */
if (signo == SIGSNDELAY && (rmp->mp_flags & DELAY_CALL)) { if (signo == SIGSNDELAY && (rmp->mp_flags & DELAY_CALL)) {
/* When getting SIGSNDELAY, the process is stopped at least until the
* receipt of the SIGSNDELAY signal is acknowledged to the kernel. The
* process is not stopped on PROC_STOP in the kernel. However, now that
* there is no longer a delay call, stop_proc() is guaranteed to
* succeed immediately.
*/
rmp->mp_flags &= ~DELAY_CALL; rmp->mp_flags &= ~DELAY_CALL;
/* assert(!(rmp->mp_flags & PROC_STOPPED));
* If the VFS_CALL flag is still set we have a process which is stopped
* and we only need to wait for a reply from VFS. We are going to check /* If the delay call was to PM, it may have resulted in a VFS call. In
* the pending signal then * that case, we must wait with further signal processing until VFS has
* replied. Stop the process.
*/ */
if (rmp->mp_flags & VFS_CALL) if (rmp->mp_flags & VFS_CALL) {
stop_proc(rmp, FALSE /*may_delay*/);
return OK; return OK;
if (rmp->mp_flags & PM_SIG_PENDING) }
panic("process_ksig: bad process state");
/* Process as many normal signals as possible. */ /* Process as many normal signals as possible. */
check_pending(rmp); check_pending(rmp);
if (rmp->mp_flags & DELAY_CALL) assert(!(rmp->mp_flags & DELAY_CALL));
panic("process_ksig: multiple delay calls?");
} }
/* See if the process is still alive */ /* See if the process is still alive */
@ -311,7 +393,7 @@ int ksig; /* non-zero means signal comes from kernel */
* context from the sigcontext structure. * context from the sigcontext structure.
* If there is insufficient stack space, kill the process. * If there is insufficient stack space, kill the process.
*/ */
int r, slot, badignore; int slot, badignore;
slot = (int) (rmp - mproc); slot = (int) (rmp - mproc);
if ((rmp->mp_flags & (IN_USE | EXITING)) != IN_USE) { if ((rmp->mp_flags & (IN_USE | EXITING)) != IN_USE) {
@ -326,8 +408,8 @@ int ksig; /* non-zero means signal comes from kernel */
sigaddset(&rmp->mp_sigtrace, signo); sigaddset(&rmp->mp_sigtrace, signo);
if (!(rmp->mp_flags & STOPPED)) if (!(rmp->mp_flags & TRACE_STOPPED))
stop_proc(rmp, signo); /* a signal causes it to stop */ trace_stop(rmp, signo); /* a signal causes it to stop */
return; return;
} }
@ -337,14 +419,20 @@ int ksig; /* non-zero means signal comes from kernel */
if(ksig) if(ksig)
sigaddset(&rmp->mp_ksigpending, signo); sigaddset(&rmp->mp_ksigpending, signo);
if (!(rmp->mp_flags & PM_SIG_PENDING)) { /* Process the signal once VFS replies. Stop the process in the
/* No delay calls: VFS_CALL implies the process called us. */ * meantime, so that it cannot make another call after the VFS reply
if ((r = sys_stop(rmp->mp_endpoint)) != OK) * comes in but before we look at its signals again. Since we always
panic("sys_stop failed: %d", r); * stop the process to deliver signals during a VFS call, the
* PROC_STOPPED flag doubles as an indicator in restart_sigs() that
rmp->mp_flags |= PM_SIG_PENDING; * signals must be rechecked after a VFS reply comes in.
*/
if (!(rmp->mp_flags & (PROC_STOPPED | DELAY_CALL))) {
/* If a VFS call is ongoing and the process is not yet stopped,
* the process must have made a call to PM. Therefore, there
* can be no delay calls in this case.
*/
stop_proc(rmp, FALSE /*delay_call*/);
} }
return; return;
} }
@ -400,7 +488,7 @@ int ksig; /* non-zero means signal comes from kernel */
return; return;
} }
if ((rmp->mp_flags & STOPPED) && signo != SIGKILL) { if ((rmp->mp_flags & TRACE_STOPPED) && signo != SIGKILL) {
/* If the process is stopped for a debugger, do not deliver any signals /* If the process is stopped for a debugger, do not deliver any signals
* (except SIGKILL) in order not to confuse the debugger. The signals * (except SIGKILL) in order not to confuse the debugger. The signals
* will be delivered using the check_pending() calls in do_trace(). * will be delivered using the check_pending() calls in do_trace().
@ -415,17 +503,13 @@ int ksig; /* non-zero means signal comes from kernel */
* applicable. This may involve a roundtrip to VFS, in which case we'll * applicable. This may involve a roundtrip to VFS, in which case we'll
* have to check back later. * have to check back later.
*/ */
if (!(rmp->mp_flags & UNPAUSED)) { if (!unpause(rmp)) {
unpause(rmp); /* not yet unpaused; continue later */
sigaddset(&rmp->mp_sigpending, signo);
if(ksig)
sigaddset(&rmp->mp_ksigpending, signo);
if (!(rmp->mp_flags & UNPAUSED)) { return;
/* not yet unpaused; continue later */
sigaddset(&rmp->mp_sigpending, signo);
if(ksig)
sigaddset(&rmp->mp_ksigpending, signo);
return;
}
} }
/* Then send the actual signal to the process, by setting up a signal /* Then send the actual signal to the process, by setting up a signal
@ -564,7 +648,6 @@ register struct mproc *rmp;
* changed. At each such place, check_pending() should be called to * changed. At each such place, check_pending() should be called to
* check for newly unblocked signals. * check for newly unblocked signals.
*/ */
int i; int i;
int ksig; int ksig;
@ -576,8 +659,14 @@ register struct mproc *rmp;
sigdelset(&rmp->mp_ksigpending, i); sigdelset(&rmp->mp_ksigpending, i);
sig_proc(rmp, i, FALSE /*trace*/, ksig); sig_proc(rmp, i, FALSE /*trace*/, ksig);
if (rmp->mp_flags & VFS_CALL) if (rmp->mp_flags & VFS_CALL) {
/* Signals must be rechecked upon return from the new
* VFS call, unless the process was killed. In both
* cases, the process is stopped.
*/
assert(rmp->mp_flags & PROC_STOPPED);
break; break;
}
} }
} }
} }
@ -590,7 +679,6 @@ struct mproc *rmp;
{ {
/* VFS has replied to a request from us; do signal-related work. /* VFS has replied to a request from us; do signal-related work.
*/ */
int r;
if (rmp->mp_flags & (VFS_CALL | EXITING)) return; if (rmp->mp_flags & (VFS_CALL | EXITING)) return;
@ -598,29 +686,27 @@ struct mproc *rmp;
/* Tracer requested exit with specific exit value */ /* Tracer requested exit with specific exit value */
exit_proc(rmp, rmp->mp_exitstatus, FALSE /*dump_core*/); exit_proc(rmp, rmp->mp_exitstatus, FALSE /*dump_core*/);
} }
else if (rmp->mp_flags & PM_SIG_PENDING) { else if (rmp->mp_flags & PROC_STOPPED) {
/* If a signal arrives while we are performing a VFS call, the process
* will always be stopped immediately. Thus, if the process is stopped
* once the reply from VFS arrives, we might have to check signals.
*/
assert(!(rmp->mp_flags & DELAY_CALL));
/* We saved signal(s) for after finishing a VFS call. Deal with this. /* We saved signal(s) for after finishing a VFS call. Deal with this.
* PM_SIG_PENDING remains set to indicate the process is still stopped. * PROC_STOPPED remains set to indicate the process is still stopped.
*/ */
check_pending(rmp); check_pending(rmp);
/* The process may now be VFS-blocked again, because a signal exited the /* Resume the process now, unless there is a reason not to. */
* process or was caught. Restart the process only when this is NOT the try_resume_proc(rmp);
* case.
*/
if (!(rmp->mp_flags & VFS_CALL)) {
rmp->mp_flags &= ~(PM_SIG_PENDING | UNPAUSED);
if ((r = sys_resume(rmp->mp_endpoint)) != OK)
panic("sys_resume failed: %d", r);
}
} }
} }
/*===========================================================================* /*===========================================================================*
* unpause * * unpause *
*===========================================================================*/ *===========================================================================*/
static void unpause(rmp) static int unpause(rmp)
struct mproc *rmp; /* which process */ struct mproc *rmp; /* which process */
{ {
/* A signal is to be sent to a process. If that process is hanging on a /* A signal is to be sent to a process. If that process is hanging on a
@ -629,43 +715,38 @@ struct mproc *rmp; /* which process */
* interruptible calls such as READs and WRITEs from pipes, ttys and the like. * interruptible calls such as READs and WRITEs from pipes, ttys and the like.
*/ */
message m; message m;
int r;
/* If we're already waiting for a delayed call, don't do anything now. */ assert(!(rmp->mp_flags & VFS_CALL));
/* If the UNPAUSED flag is set, VFS replied to an earlier unpause request. */
if (rmp->mp_flags & UNPAUSED) {
assert((rmp->mp_flags & (DELAY_CALL | PROC_STOPPED)) == PROC_STOPPED);
return TRUE;
}
/* If the process is already stopping, don't do anything now. */
if (rmp->mp_flags & DELAY_CALL) if (rmp->mp_flags & DELAY_CALL)
return; return FALSE;
/* Check to see if process is hanging on a WAIT or SIGSUSPEND call. */ /* Check to see if process is hanging on a WAIT or SIGSUSPEND call. */
if (rmp->mp_flags & (WAITING | SIGSUSPENDED)) { if (rmp->mp_flags & (WAITING | SIGSUSPENDED)) {
/* Stop process from running. No delay calls: it called us. */ /* Stop the process from running. Do not interrupt the actual call yet.
if ((r = sys_stop(rmp->mp_endpoint)) != OK) * sig_send() will interrupt the call and resume the process afterward.
panic("sys_stop failed: %d", r); * No delay calls: we know for a fact that the process called us.
rmp->mp_flags |= UNPAUSED;
/* We interrupt the actual call from sig_send() below. */
return;
}
/* Not paused in PM. Let VFS try to unpause the process. */
if (!(rmp->mp_flags & PM_SIG_PENDING)) {
/* Stop process from running. */
r = sys_delay_stop(rmp->mp_endpoint);
/* If the process is still busy sending a message, the kernel will give
* us EBUSY now and send a SIGSNDELAY to the process as soon as sending
* is done.
*/ */
if (r == EBUSY) { stop_proc(rmp, FALSE /*may_delay*/);
rmp->mp_flags |= DELAY_CALL;
return; return TRUE;
}
else if (r != OK) panic("sys_stop failed: %d", r);
rmp->mp_flags |= PM_SIG_PENDING;
} }
/* Not paused in PM. Let VFS try to unpause the process. The process needs to
* be stopped for this. If it is not already stopped, try to stop it now. If
* that does not succeed immediately, postpone signal delivery.
*/
if (!(rmp->mp_flags & PROC_STOPPED) && !stop_proc(rmp, TRUE /*may_delay*/))
return FALSE;
m.m_type = PM_UNPAUSE; m.m_type = PM_UNPAUSE;
m.PM_PROC = rmp->mp_endpoint; m.PM_PROC = rmp->mp_endpoint;
@ -673,6 +754,8 @@ struct mproc *rmp; /* which process */
/* Also tell VM. */ /* Also tell VM. */
vm_notify_sig_wrapper(rmp->mp_endpoint); vm_notify_sig_wrapper(rmp->mp_endpoint);
return FALSE;
} }
/*===========================================================================* /*===========================================================================*
@ -688,8 +771,7 @@ int signo; /* signal to send to process (1 to _NSIG-1) */
struct sigmsg sigmsg; struct sigmsg sigmsg;
int r, sigflags, slot; int r, sigflags, slot;
if (!(rmp->mp_flags & UNPAUSED)) assert(rmp->mp_flags & PROC_STOPPED);
panic("sig_send: process not unpaused");
sigflags = rmp->mp_sigact[signo].sa_flags; sigflags = rmp->mp_sigact[signo].sa_flags;
slot = (int) (rmp - mproc); slot = (int) (rmp - mproc);
@ -718,8 +800,9 @@ int signo; /* signal to send to process (1 to _NSIG-1) */
/* Ask the kernel to deliver the signal */ /* Ask the kernel to deliver the signal */
r = sys_sigsend(rmp->mp_endpoint, &sigmsg); r = sys_sigsend(rmp->mp_endpoint, &sigmsg);
/* sys_sigsend can fail legitimately with EFAULT or ENOMEM if /* sys_sigsend can fail legitimately with EFAULT or ENOMEM if the process
* the process memory can't accomodate the signal handler. * memory can't accommodate the signal handler. The target process will be
* killed in that case, so do not bother interrupting or resuming it.
*/ */
if(r == EFAULT || r == ENOMEM) { if(r == EFAULT || r == ENOMEM) {
return(FALSE); return(FALSE);
@ -734,14 +817,22 @@ int signo; /* signal to send to process (1 to _NSIG-1) */
rmp->mp_flags &= ~(WAITING | SIGSUSPENDED); rmp->mp_flags &= ~(WAITING | SIGSUSPENDED);
setreply(slot, EINTR); setreply(slot, EINTR);
}
/* Was the process stopped just for this signal? Then resume it. */ /* The process must just have been stopped by unpause(), which means
if ((rmp->mp_flags & (PM_SIG_PENDING | UNPAUSED)) == UNPAUSED) { * that the UNPAUSE flag is not set.
rmp->mp_flags &= ~UNPAUSED; */
assert(!(rmp->mp_flags & UNPAUSED));
if ((r = sys_resume(rmp->mp_endpoint)) != OK) try_resume_proc(rmp);
panic("sys_resume failed: %d", r);
assert(!(rmp->mp_flags & PROC_STOPPED));
} else {
/* If the process was not suspended in PM, VFS must first have
* confirmed that it has tried to unsuspend any blocking call. Thus, we
* got here from restart_sigs() as part of handling PM_UNPAUSE_REPLY,
* and restart_sigs() will resume the process later.
*/
assert(rmp->mp_flags & UNPAUSED);
} }
return(TRUE); return(TRUE);

13
servers/pm/trace.c
View file

@ -42,7 +42,6 @@ int do_trace()
register struct mproc *child; register struct mproc *child;
struct ptrace_range pr; struct ptrace_range pr;
int i, r, req; int i, r, req;
message m;
req = m_in.request; req = m_in.request;
@ -137,7 +136,7 @@ int do_trace()
if ((child = find_proc(m_in.pid)) == NULL) return(ESRCH); if ((child = find_proc(m_in.pid)) == NULL) return(ESRCH);
if (child->mp_flags & EXITING) return(ESRCH); if (child->mp_flags & EXITING) return(ESRCH);
if (child->mp_tracer != who_p) return(ESRCH); if (child->mp_tracer != who_p) return(ESRCH);
if (!(child->mp_flags & STOPPED)) return(EBUSY); if (!(child->mp_flags & TRACE_STOPPED)) return(EBUSY);
switch (req) { switch (req) {
case T_EXIT: /* exit */ case T_EXIT: /* exit */
@ -202,7 +201,7 @@ int do_trace()
} }
/* Resume the child as if nothing ever happened. */ /* Resume the child as if nothing ever happened. */
child->mp_flags &= ~STOPPED; child->mp_flags &= ~TRACE_STOPPED;
child->mp_trace_flags = 0; child->mp_trace_flags = 0;
check_pending(child); check_pending(child);
@ -229,7 +228,7 @@ int do_trace()
} }
} }
child->mp_flags &= ~STOPPED; child->mp_flags &= ~TRACE_STOPPED;
check_pending(child); check_pending(child);
@ -243,9 +242,9 @@ int do_trace()
} }
/*===========================================================================* /*===========================================================================*
* stop_proc * * trace_stop *
*===========================================================================*/ *===========================================================================*/
void stop_proc(rmp, signo) void trace_stop(rmp, signo)
register struct mproc *rmp; register struct mproc *rmp;
int signo; int signo;
{ {
@ -257,7 +256,7 @@ int signo;
r = sys_trace(T_STOP, rmp->mp_endpoint, 0L, (long *) 0); r = sys_trace(T_STOP, rmp->mp_endpoint, 0L, (long *) 0);
if (r != OK) panic("sys_trace failed: %d", r); if (r != OK) panic("sys_trace failed: %d", r);
rmp->mp_flags |= STOPPED; rmp->mp_flags |= TRACE_STOPPED;
if (wait_test(rpmp, rmp)) { if (wait_test(rpmp, rmp)) {
sigdelset(&rmp->mp_sigtrace, signo); sigdelset(&rmp->mp_sigtrace, signo);

2
servers/procfs/pid.c
View file

@ -73,7 +73,7 @@ static void pid_psinfo(int i)
if (!task) { if (!task) {
if (is_zombie(i)) if (is_zombie(i))
state = STATE_ZOMBIE; /* zombie */ state = STATE_ZOMBIE; /* zombie */
else if (mproc[pi].mp_flags & STOPPED) else if (mproc[pi].mp_flags & TRACE_STOPPED)
state = STATE_STOP; /* stopped (traced) */ state = STATE_STOP; /* stopped (traced) */
else if (proc[i].p_rts_flags == 0) else if (proc[i].p_rts_flags == 0)
state = STATE_RUN; /* in run-queue */ state = STATE_RUN; /* in run-queue */

2
test/Makefile
View file

@ -57,7 +57,7 @@ MINIX_TESTS= \
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 \ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 \
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 \ 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 \
41 42 43 44 45 46 48 49 50 52 53 54 55 56 58 59 60 \ 41 42 43 44 45 46 48 49 50 52 53 54 55 56 58 59 60 \
61 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 61 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79
.if ${MACHINE_ARCH} == "i386" .if ${MACHINE_ARCH} == "i386"
MINIX_TESTS+= \ MINIX_TESTS+= \

2
test/run
View file

@ -28,7 +28,7 @@ rootscripts="testisofs testvnd"
alltests="1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 \ alltests="1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 \
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 \ 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 \
41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 \ 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 \
61 62 63 64 65 66 67 68 69 70 71 72 75 76 77 78 \ 61 62 63 64 65 66 67 68 69 70 71 72 75 76 77 78 79 \
sh1 sh2 interp mfs isofs vnd" sh1 sh2 interp mfs isofs vnd"
tests_no=`expr 0` tests_no=`expr 0`

497
test/test79.c Normal file
View file

@ -0,0 +1,497 @@
/* Tests for PM signal handling robustness - by D.C. van Moolenbroek */
/*
* The signal handling code must not rely on priorities assigned to services,
* and so, this test (like any test!) must also pass if PM and/or VFS are not
* given a fixed high priority. A good way to verify this is to let PM and VFS
* be scheduled by SCHED rather than KERNEL, and to give them the same priority
* as (or slightly lower than) normal user processes. Note that if VFS is
* configured to use a priority *far lower* than user processes, starvation may
* cause this test not to complete in some scenarios. In that case, Ctrl+C
* should still be able to kill the test.
*/
#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/utsname.h>
#define ITERATIONS 1
#include "common.h"
#define NR_SIGNALS 20000
#define MAX_SIGNALERS 3
static const int signaler_sig[MAX_SIGNALERS] = { SIGUSR1, SIGUSR2, SIGHUP };
static pid_t signaler_pid[MAX_SIGNALERS];
static int sig_counter;
enum {
JOB_RUN = 0,
JOB_CALL_PM,
JOB_CALL_VFS,
JOB_SET_MASK,
JOB_BLOCK_PM,
JOB_BLOCK_VFS,
JOB_CALL_PM_VFS,
NR_JOBS
};
#define OPT_NEST 0x1
#define OPT_ALARM 0x2
#define OPT_ALL 0x3
struct link {
pid_t pid;
int sndfd;
int rcvfd;
};
/*
* Spawn a child process, with a pair of pipes to talk to it bidirectionally.
*/
static void
spawn(struct link *link, void (*proc)(struct link *))
{
int up[2], dn[2];
fflush(stdout);
fflush(stderr);
if (pipe(up) != 0) e(0);
if (pipe(dn) != 0) e(0);
link->pid = fork();
switch (link->pid) {
case 0:
close(up[1]);
close(dn[0]);
link->rcvfd = up[0];
link->sndfd = dn[1];
errct = 0;
proc(link);
/* Close our pipe FDs on exit, so that we can make zombies. */
exit(errct);
case -1:
e(0);
break;
}
close(up[0]);
close(dn[1]);
link->sndfd = up[1];
link->rcvfd = dn[0];
}
/*
* Wait for a child process to terminate, and clean up.
*/
static void
collect(struct link *link)
{
int status;
close(link->sndfd);
close(link->rcvfd);
if (waitpid(link->pid, &status, 0) <= 0) e(0);
if (!WIFEXITED(status)) e(0);
else errct += WEXITSTATUS(status);
}
/*
* Forcibly terminate a child process, and clean up.
*/
static void
terminate(struct link *link)
{
int status;
if (kill(link->pid, SIGKILL) != 0) e(0);
close(link->sndfd);
close(link->rcvfd);
if (waitpid(link->pid, &status, 0) <= 0) e(0);
if (WIFSIGNALED(status)) {
if (WTERMSIG(status) != SIGKILL) e(0);
} else {
if (!WIFEXITED(status)) e(0);
else errct += WEXITSTATUS(status);
}
}
/*
* Send an integer value to the child or parent.
*/
static void
snd(struct link *link, int val)
{
if (write(link->sndfd, (void *) &val, sizeof(val)) != sizeof(val))
e(0);
}
/*
* Receive an integer value from the child or parent, or -1 on EOF.
*/
static int
rcv(struct link *link)
{
int r, val;
if ((r = read(link->rcvfd, (void *) &val, sizeof(val))) == 0)
return -1;
if (r != sizeof(val)) e(0);
return val;
}
/*
* Set a signal handler for a particular signal, blocking either all or no
* signals when the signal handler is invoked.
*/
static void
set_handler(int sig, void (*proc)(int), int block)
{
struct sigaction act;
memset(&act, 0, sizeof(act));
if (block) sigfillset(&act.sa_mask);
act.sa_handler = proc;
if (sigaction(sig, &act, NULL) != 0) e(0);
}
/*
* Generic signal handler for the worker process.
*/
static void
worker_handler(int sig)
{
int i;
switch (sig) {
case SIGUSR1:
case SIGUSR2:
case SIGHUP:
for (i = 0; i < MAX_SIGNALERS; i++) {
if (signaler_sig[i] != sig) continue;
if (signaler_pid[i] == -1) e(0);
else if (kill(signaler_pid[i], SIGUSR1) != 0) e(0);
break;
}
if (i == MAX_SIGNALERS) e(0);
break;
case SIGTERM:
exit(errct);
break;
case SIGALRM:
/* Do nothing. */
break;
default:
e(0);
}
}
/*
* Procedure for the worker process. Sets up its own environment using
* information sent to it by the parent, sends an acknowledgement to the
* parent, and loops executing the job given to it until a SIGTERM comes in.
*/
static void __dead
worker_proc(struct link *parent)
{
struct utsname name;
struct itimerval it;
struct timeval tv;
sigset_t set, oset;
uid_t uid;
int i, job, options;
job = rcv(parent);
options = rcv(parent);
for (i = 0; i < MAX_SIGNALERS; i++) {
set_handler(signaler_sig[i], worker_handler,
!(options & OPT_NEST));
signaler_pid[i] = rcv(parent);
}
set_handler(SIGTERM, worker_handler, 1 /* block */);
set_handler(SIGALRM, worker_handler, !(options & OPT_NEST));
snd(parent, 0);
if (options & OPT_ALARM) {
/* The timer would kill wimpy platforms such as ARM. */
if (uname(&name) < 0) e(0);
if (strcmp(name.machine, "arm")) {
it.it_value.tv_sec = 0;
it.it_value.tv_usec = 1;
it.it_interval.tv_sec = 0;
it.it_interval.tv_usec = 1;
if (setitimer(ITIMER_REAL, &it, NULL) != 0) e(0);
}
}
switch (job) {
case JOB_RUN:
for (;;);
break;
case JOB_CALL_PM:
/*
* Part of the complication of the current system in PM comes
* from the fact that when a process is being stopped, it might
* already have started sending a message. That message will
* arrive at its destination regardless of the process's run
* state. PM must avoid setting up a signal handler (and
* changing the process's signal mask as part of that) if such
* a message is still in transit, because that message might,
* for example, query (or even change) the signal mask.
*/
for (;;) {
if (sigprocmask(SIG_BLOCK, NULL, &set) != 0) e(0);
if (sigismember(&set, SIGUSR1)) e(0);
}
break;
case JOB_CALL_VFS:
for (;;) {
tv.tv_sec = 0;
tv.tv_usec = 0;
select(0, NULL, NULL, NULL, &tv);
}
break;
case JOB_SET_MASK:
for (;;) {
sigfillset(&set);
if (sigprocmask(SIG_SETMASK, &set, &oset) != 0) e(0);
if (sigprocmask(SIG_SETMASK, &oset, NULL) != 0) e(0);
}
break;
case JOB_BLOCK_PM:
for (;;) {
sigemptyset(&set);
sigsuspend(&set);
}
break;
case JOB_BLOCK_VFS:
for (;;)
select(0, NULL, NULL, NULL, NULL);
break;
case JOB_CALL_PM_VFS:
uid = getuid();
for (;;)
setuid(uid);
default:
e(0);
exit(1);
}
}
/*
* Signal handler procedure for the signaler processes, counting the number of
* signals received from the worker process.
*/
static void
signaler_handler(int sig)
{
sig_counter++;
}
/*
* Procedure for the signaler processes. Gets the pid of the worker process
* and the signal to use, and then repeatedly sends that signal to the worker
* process, waiting for a SIGUSR1 signal back from the worker before
* continuing. This signal ping-pong is repeated for a set number of times.
*/
static void
signaler_proc(struct link *parent)
{
sigset_t set, oset;
pid_t pid;
int i, sig, nr;
pid = rcv(parent);
sig = rcv(parent);
nr = rcv(parent);
sig_counter = 0;
sigfillset(&set);
if (sigprocmask(SIG_SETMASK, &set, &oset) != 0) e(0);
set_handler(SIGUSR1, signaler_handler, 1 /*block*/);
for (i = 0; nr == 0 || i < nr; i++) {
if (sig_counter != i) e(0);
if (kill(pid, sig) != 0 && nr > 0) e(0);
sigsuspend(&oset);
}
if (sig_counter != nr) e(0);
}
/*
* Set up the worker and signaler processes, wait for the signaler processes to
* do their work and terminate, and then terminate the worker process.
*/
static void
sub79a(int job, int signalers, int options)
{
struct link worker, signaler[MAX_SIGNALERS];
int i;
spawn(&worker, worker_proc);
snd(&worker, job);
snd(&worker, options);
for (i = 0; i < signalers; i++) {
spawn(&signaler[i], signaler_proc);
snd(&worker, signaler[i].pid);
}
for (; i < MAX_SIGNALERS; i++)
snd(&worker, -1);
if (rcv(&worker) != 0) e(0);
for (i = 0; i < signalers; i++) {
snd(&signaler[i], worker.pid);
snd(&signaler[i], signaler_sig[i]);
snd(&signaler[i], NR_SIGNALS);
}
for (i = 0; i < signalers; i++)
collect(&signaler[i]);
if (kill(worker.pid, SIGTERM) != 0) e(0);
collect(&worker);
}
/*
* Stress test for signal handling. One worker process gets signals from up to
* three signaler processes while performing one of a number of jobs. It
* replies to each signal by signaling the source, thus creating a ping-pong
* effect for each of the signaler processes. The signal ping-ponging is
* supposed to be reliable, and the most important aspect of the test is that
* no signals get lost. The test is performed a number of times, varying the
* job executed by the worker process, the number of signalers, whether signals
* are blocked while executing a signal handler in the worker, and whether the
* worker process has a timer running at high frequency.
*/
static void
test79a(void)
{
int job, signalers, options;
subtest = 1;
for (options = 0; options <= OPT_ALL; options++)
for (signalers = 1; signalers <= MAX_SIGNALERS; signalers++)
for (job = 0; job < NR_JOBS; job++)
sub79a(job, signalers, options);
}
/*
* Set up the worker process and optionally a signaler process, wait for a
* predetermined amount of time, and then kill all the child processes.
*/
static void
sub79b(int job, int use_signaler, int options)
{
struct link worker, signaler;
struct timeval tv;
int i;
spawn(&worker, worker_proc);
snd(&worker, job);
snd(&worker, options);
if ((i = use_signaler) != 0) {
spawn(&signaler, signaler_proc);
snd(&worker, signaler.pid);
}
for (; i < MAX_SIGNALERS; i++)
snd(&worker, -1);
if (rcv(&worker) != 0) e(0);
if (use_signaler) {
snd(&signaler, worker.pid);
snd(&signaler, signaler_sig[0]);
snd(&signaler, 0);
}
/* Use select() so that we can verify we don't get signals. */
tv.tv_sec = 0;
tv.tv_usec = 100000;
if (select(0, NULL, NULL, NULL, &tv) != 0) e(0);
terminate(&worker);
if (use_signaler)
terminate(&signaler);
}
/*
* This test is similar to the previous one, except that we now kill the worker
* process after a while. This should trigger various process transitions to
* the exiting state. Not much can be verified from this test program, but we
* intend to trigger as many internal state verification statements of PM
* itself as possible this way. A signaler process is optional in this test,
* and if used, it will not stop after a predetermined number of signals.
*/
static void
test79b(void)
{
int job, signalers, options;
subtest = 2;
for (options = 0; options <= OPT_ALL; options++)
for (signalers = 0; signalers <= 1; signalers++)
for (job = 0; job < NR_JOBS; job++)
sub79b(job, signalers, options);
}
/*
* PM signal handling robustness test program.
*/
int
main(int argc, char **argv)
{
int i, m;
start(79);
if (argc == 2)
m = atoi(argv[1]);
else
m = 0xFF;
for (i = 0; i < ITERATIONS; i++) {
if (m & 0x01) test79a();
if (m & 0x02) test79b();
}
quit();
}