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Unlock of shared memory zones on process crash.

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If process exited abnormally while holding lock on some shared memory zone -
unlock it.  It may be not safe thing to do (as crash with lock held may
result in corrupted shared memory structure, and other processes will
subsequently crash while trying to access shared data), therefore complain
loudly if unlock succeeds.
This commit is contained in:
Maxim Dounin 2011-11-23 14:09:19 +00:00
parent ddb7cd1c41
commit 13717da19e
1 changed files with 50 additions and 11 deletions
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61
src/os/unix/ngx_process.c
View File

@ -22,6 +22,7 @@ typedef struct {
static void ngx_execute_proc(ngx_cycle_t *cycle, void *data);
static void ngx_signal_handler(int signo);
static void ngx_process_get_status(void);
static void ngx_unlock_mutexes(ngx_pid_t pid);
int ngx_argc;
@ -497,17 +498,6 @@ ngx_process_get_status(void)
}
if (ngx_accept_mutex_ptr) {
/*
* unlock the accept mutex if the abnormally exited process
* held it
*/
ngx_shmtx_force_unlock(&ngx_accept_mutex, pid);
}
one = 1;
process = "unknown process";
@ -545,6 +535,55 @@ ngx_process_get_status(void)
process, pid, WEXITSTATUS(status));
ngx_processes[i].respawn = 0;
}
ngx_unlock_mutexes(pid);
}
}
static void
ngx_unlock_mutexes(ngx_pid_t pid)
{
ngx_uint_t i;
ngx_shm_zone_t *shm_zone;
ngx_list_part_t *part;
ngx_slab_pool_t *sp;
/*
* unlock the accept mutex if the abnormally exited process
* held it
*/
if (ngx_accept_mutex_ptr) {
ngx_shmtx_force_unlock(&ngx_accept_mutex, pid);
}
/*
* unlock shared memory mutexes if held by the abnormally exited
* process
*/
part = (ngx_list_part_t *) &ngx_cycle->shared_memory.part;
shm_zone = part->elts;
for (i = 0; /* void */ ; i++) {
if (i >= part->nelts) {
if (part->next == NULL) {
break;
}
part = part->next;
shm_zone = part->elts;
i = 0;
}
sp = (ngx_slab_pool_t *) shm_zone[i].shm.addr;
if (ngx_shmtx_force_unlock(&sp->mutex, pid)) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
"shared memory zone \"%V\" was locked by %P",
&shm_zone[i].shm.name, pid);
}
}
}