minix/lib/sysutil/asynsend.c
David van Moolenbroek b423d7b477 Merge of David's ptrace branch. Summary:
o Support for ptrace T_ATTACH/T_DETACH and T_SYSCALL
o PM signal handling logic should now work properly, even with debuggers
  being present
o Asynchronous PM/VFS protocol, full IPC support for senda(), and
  AMF_NOREPLY senda() flag

DETAILS

Process stop and delay call handling of PM:
o Added sys_runctl() kernel call with sys_stop() and sys_resume()
  aliases, for PM to stop and resume a process
o Added exception for sending/syscall-traced processes to sys_runctl(),
  and matching SIGKREADY pseudo-signal to PM
o Fixed PM signal logic to deal with requests from a process after
  stopping it (so-called "delay calls"), using the SIGKREADY facility
o Fixed various PM panics due to race conditions with delay calls versus
  VFS calls
o Removed special PRIO_STOP priority value
o Added SYS_LOCK RTS kernel flag, to stop an individual process from
  running while modifying its process structure

Signal and debugger handling in PM:
o Fixed debugger signals being dropped if a second signal arrives when
  the debugger has not retrieved the first one
o Fixed debugger signals being sent to the debugger more than once
o Fixed debugger signals unpausing process in VFS; removed PM_UNPAUSE_TR
  protocol message
o Detached debugger signals from general signal logic and from being
  blocked on VFS calls, meaning that even VFS can now be traced
o Fixed debugger being unable to receive more than one pending signal in
  one process stop
o Fixed signal delivery being delayed needlessly when multiple signals
  are pending
o Fixed wait test for tracer, which was returning for children that were
  not waited for
o Removed second parallel pending call from PM to VFS for any process
o Fixed process becoming runnable between exec() and debugger trap
o Added support for notifying the debugger before the parent when a
  debugged child exits
o Fixed debugger death causing child to remain stopped forever
o Fixed consistently incorrect use of _NSIG

Extensions to ptrace():
o Added T_ATTACH and T_DETACH ptrace request, to attach and detach a
  debugger to and from a process
o Added T_SYSCALL ptrace request, to trace system calls
o Added T_SETOPT ptrace request, to set trace options
o Added TO_TRACEFORK trace option, to attach automatically to children
  of a traced process
o Added TO_ALTEXEC trace option, to send SIGSTOP instead of SIGTRAP upon
  a successful exec() of the tracee
o Extended T_GETUSER ptrace support to allow retrieving a process's priv
  structure
o Removed T_STOP ptrace request again, as it does not help implementing
  debuggers properly
o Added MINIX3-specific ptrace test (test42)
o Added proper manual page for ptrace(2)

Asynchronous PM/VFS interface:
o Fixed asynchronous messages not being checked when receive() is called
  with an endpoint other than ANY
o Added AMF_NOREPLY senda() flag, preventing such messages from
  satisfying the receive part of a sendrec()
o Added asynsend3() that takes optional flags; asynsend() is now a
  #define passing in 0 as third parameter
o Made PM/VFS protocol asynchronous; reintroduced tell_fs()
o Made PM_BASE request/reply number range unique
o Hacked in a horrible temporary workaround into RS to deal with newly
  revealed RS-PM-VFS race condition triangle until VFS is asynchronous

System signal handling:
o Fixed shutdown logic of device drivers; removed old SIGKSTOP signal
o Removed is-superuser check from PM's do_procstat() (aka getsigset())
o Added sigset macros to allow system processes to deal with the full
  signal set, rather than just the POSIX subset

Miscellaneous PM fixes:
o Split do_getset into do_get and do_set, merging common code and making
  structure clearer
o Fixed setpriority() being able to put to sleep processes using an
  invalid parameter, or revive zombie processes
o Made find_proc() global; removed obsolete proc_from_pid()
o Cleanup here and there

Also included:
o Fixed false-positive boot order kernel warning
o Removed last traces of old NOTIFY_FROM code

THINGS OF POSSIBLE INTEREST

o It should now be possible to run PM at any priority, even lower than
  user processes
o No assumptions are made about communication speed between PM and VFS,
  although communication must be FIFO
o A debugger will now receive incoming debuggee signals at kill time
  only; the process may not yet be fully stopped
o A first step has been made towards making the SYSTEM task preemptible
2009-09-30 09:57:22 +00:00

140 lines
2.6 KiB
C

#define _MINIX 1
#define _SYSTEM 1
#include <minix/config.h>
#include <ansi.h>
#include <assert.h>
#include <sys/types.h>
#include <minix/const.h>
#include <minix/type.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <minix/syslib.h>
#include <minix/sysutil.h>
#include <limits.h>
#include <errno.h>
#define ASYN_NR 100
PRIVATE asynmsg_t msgtable[ASYN_NR];
PRIVATE int first_slot= 0, next_slot= 0;
PUBLIC int asynsend3(dst, mp, fl)
endpoint_t dst;
message *mp;
int fl;
{
int r, src_ind, dst_ind;
unsigned flags;
static int first = 1;
static int inside = 0;
int len;
/* printf() causes asynsend? */
if(inside) {
exit(1);
}
inside = 1;
if(first) {
int i;
for(i = 0; i < ASYN_NR; i++) {
msgtable[i].flags = AMF_EMPTY;
}
first = 0;
}
/* Update first_slot */
for (; first_slot < next_slot; first_slot++)
{
flags= msgtable[first_slot].flags;
if ((flags & (AMF_VALID|AMF_DONE)) == (AMF_VALID|AMF_DONE))
{
if (msgtable[first_slot].result != OK)
{
#if 0
printf(
"asynsend: found completed entry %d with error %d\n",
first_slot,
msgtable[first_slot].result);
#endif
}
continue;
}
if (flags != AMF_EMPTY)
break;
}
if (first_slot >= next_slot)
{
/* Reset first_slot and next_slot */
next_slot= first_slot= 0;
}
if (next_slot >= ASYN_NR)
{
/* Tell the kernel to stop processing */
r= senda(NULL, 0);
if (r != OK)
panic(__FILE__, "asynsend: senda failed", r);
dst_ind= 0;
for (src_ind= first_slot; src_ind<next_slot; src_ind++)
{
flags= msgtable[src_ind].flags;
if ((flags & (AMF_VALID|AMF_DONE)) ==
(AMF_VALID|AMF_DONE))
{
if (msgtable[src_ind].result != OK)
{
#if 0
printf(
"asynsend: found completed entry %d with error %d\n",
src_ind,
msgtable[src_ind].result);
#endif
}
continue;
}
if (flags == AMF_EMPTY)
continue;
#if 0
printf("asynsend: copying entry %d to %d\n",
src_ind, dst_ind);
#endif
if (src_ind != dst_ind)
msgtable[dst_ind]= msgtable[src_ind];
dst_ind++;
}
first_slot= 0;
next_slot= dst_ind;
if (next_slot >= ASYN_NR)
panic(__FILE__, "asynsend: msgtable full", NO_NUM);
}
fl |= AMF_VALID;
msgtable[next_slot].dst= dst;
msgtable[next_slot].msg= *mp;
msgtable[next_slot].flags= fl; /* Has to be last. The kernel
* scans this table while we
* are sleeping.
*/
next_slot++;
assert(first_slot < ASYN_NR);
assert(next_slot >= first_slot);
len = next_slot-first_slot;
assert(first_slot + len <= ASYN_NR);
/* Tell the kernel to rescan the table */
r = senda(msgtable+first_slot, len);
inside = 0;
return r;
}