Merge branch 'ti/glibc-stdio-mutex-from-signal-handler' into maint

Allocation related functions and stdio are unsafe things to call
inside a signal handler, and indeed killing the pager can cause
glibc to deadlock waiting on allocation mutex as our signal handler
tries to free() some data structures in wait_for_pager().  Reduce
these unsafe calls.

* ti/glibc-stdio-mutex-from-signal-handler:
  pager: don't use unsafe functions in signal handlers
This commit is contained in:
Junio C Hamano 2015-10-16 14:32:41 -07:00
Родитель f4892a3c28 507d7804c0
Коммит 267ebf6c84
3 изменённых файлов: 34 добавлений и 14 удалений

22
pager.c
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@ -14,19 +14,29 @@
static const char *pager_argv[] = { NULL, NULL };
static struct child_process pager_process = CHILD_PROCESS_INIT;
static void wait_for_pager(void)
static void wait_for_pager(int in_signal)
{
fflush(stdout);
fflush(stderr);
if (!in_signal) {
fflush(stdout);
fflush(stderr);
}
/* signal EOF to pager */
close(1);
close(2);
finish_command(&pager_process);
if (in_signal)
finish_command_in_signal(&pager_process);
else
finish_command(&pager_process);
}
static void wait_for_pager_atexit(void)
{
wait_for_pager(0);
}
static void wait_for_pager_signal(int signo)
{
wait_for_pager();
wait_for_pager(1);
sigchain_pop(signo);
raise(signo);
}
@ -90,7 +100,7 @@ void setup_pager(void)
/* this makes sure that the parent terminates after the pager */
sigchain_push_common(wait_for_pager_signal);
atexit(wait_for_pager);
atexit(wait_for_pager_atexit);
}
int pager_in_use(void)

Просмотреть файл

@ -18,26 +18,27 @@ struct child_to_clean {
static struct child_to_clean *children_to_clean;
static int installed_child_cleanup_handler;
static void cleanup_children(int sig)
static void cleanup_children(int sig, int in_signal)
{
while (children_to_clean) {
struct child_to_clean *p = children_to_clean;
children_to_clean = p->next;
kill(p->pid, sig);
free(p);
if (!in_signal)
free(p);
}
}
static void cleanup_children_on_signal(int sig)
{
cleanup_children(sig);
cleanup_children(sig, 1);
sigchain_pop(sig);
raise(sig);
}
static void cleanup_children_on_exit(void)
{
cleanup_children(SIGTERM);
cleanup_children(SIGTERM, 0);
}
static void mark_child_for_cleanup(pid_t pid)
@ -220,7 +221,7 @@ static inline void set_cloexec(int fd)
fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
}
static int wait_or_whine(pid_t pid, const char *argv0)
static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
{
int status, code = -1;
pid_t waiting;
@ -228,6 +229,8 @@ static int wait_or_whine(pid_t pid, const char *argv0)
while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
; /* nothing */
if (in_signal)
return 0;
if (waiting < 0) {
failed_errno = errno;
@ -437,7 +440,7 @@ fail_pipe:
* At this point we know that fork() succeeded, but execvp()
* failed. Errors have been reported to our stderr.
*/
wait_or_whine(cmd->pid, cmd->argv[0]);
wait_or_whine(cmd->pid, cmd->argv[0], 0);
failed_errno = errno;
cmd->pid = -1;
}
@ -536,12 +539,18 @@ fail_pipe:
int finish_command(struct child_process *cmd)
{
int ret = wait_or_whine(cmd->pid, cmd->argv[0]);
int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
argv_array_clear(&cmd->args);
argv_array_clear(&cmd->env_array);
return ret;
}
int finish_command_in_signal(struct child_process *cmd)
{
return wait_or_whine(cmd->pid, cmd->argv[0], 1);
}
int run_command(struct child_process *cmd)
{
int code;
@ -772,7 +781,7 @@ error:
int finish_async(struct async *async)
{
#ifdef NO_PTHREADS
return wait_or_whine(async->pid, "child process");
return wait_or_whine(async->pid, "child process", 0);
#else
void *ret = (void *)(intptr_t)(-1);

Просмотреть файл

@ -50,6 +50,7 @@ void child_process_init(struct child_process *);
int start_command(struct child_process *);
int finish_command(struct child_process *);
int finish_command_in_signal(struct child_process *);
int run_command(struct child_process *);
/*