minix/servers/vfs/gcov.c
David van Moolenbroek 723e51327f VFS: worker thread model overhaul
The main purpose of this patch is to fix handling of unpause calls
from PM while another call is ongoing. The solution to this problem
sparked a full revision of the threading model, consisting of a large
number of related changes:

- all active worker threads are now always associated with a process,
  and every process has at most one active thread working for it;
- the process lock is always held by a process's worker thread;
- a process can now have both normal work and postponed PM work
  associated to it;
- timer expiry and non-postponed PM work is done from the main thread;
- filp garbage collection is done from a thread associated with VFS;
- reboot calls from PM are now done from a thread associated with PM;
- the DS events handler is protected from starting multiple threads;
- support for a system worker thread has been removed;
- the deadlock recovery thread has been replaced by a parameter to the
  worker_start() function; the number of worker threads has
  consequently been increased by one;
- saving and restoring of global but per-thread variables is now
  centralized in worker_suspend() and worker_resume(); err_code is now
  saved and restored in all cases;
- the concept of jobs has been removed, and job_m_in now points to a
  message stored in the worker thread structure instead;
- the PM lock has been removed;
- the separate exec lock has been replaced by a lock on the VM
  process, which was already being locked for exec calls anyway;
- PM_UNPAUSE is now processed as a postponed PM request, from a thread
  associated with the target process;
- the FP_DROP_WORK flag has been removed, since it is no longer more
  than just an optimization and only applied to processes operating on
  a pipe when getting killed;
- assignment to "fp" now takes place only when obtaining new work in
  the main thread or a worker thread, when resuming execution of a
  thread, and in the special case of exiting processes during reboot;
- there are no longer special cases where the yield() call is used to
  force a thread to run.

Change-Id: I7a97b9b95c2450454a9b5318dfa0e6150d4e6858
2014-02-18 11:25:03 +01:00

67 lines
1.6 KiB
C

#include "fs.h"
#include "file.h"
int gcov_flush(cp_grant_id_t grantid, size_t size );
/*===========================================================================*
* do_gcov_flush *
*===========================================================================*/
int do_gcov_flush()
{
/* A userland tool has requested the gcov data from another
* process (possibly vfs itself). Grant the target process
* access to the supplied buffer, and perform the call that
* makes the target copy its buffer to the caller (incl vfs
* itself).
*/
struct fproc *rfp;
ssize_t size;
cp_grant_id_t grantid;
int r, n;
pid_t target;
message m;
vir_bytes buf;
size = job_m_in.GCOV_BUFF_SZ;
target = job_m_in.GCOV_PID;
buf = (vir_bytes) job_m_in.GCOV_BUFF_P;
/* If the wrong process is sent to, the system hangs; so make this root-only.
*/
if (!super_user) return(EPERM);
/* Find target gcov process. */
for(n = 0; n < NR_PROCS; n++) {
if(fproc[n].fp_endpoint != NONE && fproc[n].fp_pid == target)
break;
}
if(n >= NR_PROCS) {
printf("VFS: gcov process %d not found\n", target);
return(ESRCH);
}
rfp = &fproc[n];
/* Grant target process to requestor's buffer. */
if ((grantid = cpf_grant_magic(rfp->fp_endpoint, who_e, buf,
size, CPF_WRITE)) < 0) {
printf("VFS: gcov_flush: grant failed\n");
return(ENOMEM);
}
if (rfp->fp_endpoint == VFS_PROC_NR) {
/* Request is for VFS itself. */
r = gcov_flush(grantid, size);
} else {
/* Perform generic GCOV request. */
m.GCOV_GRANT = grantid;
m.GCOV_BUFF_SZ = size;
r = _taskcall(rfp->fp_endpoint, COMMON_REQ_GCOV_DATA, &m);
}
cpf_revoke(grantid);
return(r);
}