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drmtest: Avoid wrong PID/TID after clone races

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Various C library implementations have various races with regards
to caching getpid() or TID inside pthread_kill() implementations.

For example see clone(2) glibc man page and pthread_kill
Bionic C library source.

Work around that by making sure correct PID/TGID and TID values
are retrieved from the kernel when re-raising the signal. It
can be delivered immediately after the clone system call while C
library cached copies have not yet been updated.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Tvrtko Ursulin 2013-12-03 16:44:55 +00:00 committed by Daniel Vetter
parent 4f990f3ad2
commit 139c72f38a
1 changed files with 9 additions and 1 deletions
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10
lib/drmtest.c
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@ -43,6 +43,8 @@
#include <stdlib.h> #include <stdlib.h>
#include <unistd.h> #include <unistd.h>
#include <sys/wait.h> #include <sys/wait.h>
#include <sys/types.h>
#include <sys/syscall.h>
#include "drmtest.h" #include "drmtest.h"
#include "i915_drm.h" #include "i915_drm.h"
@ -1479,6 +1481,8 @@ static void igt_atexit_handler(void)
static void fatal_sig_handler(int sig) static void fatal_sig_handler(int sig)
{ {
pid_t pid, tid;
restore_all_sig_handler(); restore_all_sig_handler();
/* /*
@ -1487,7 +1491,11 @@ static void fatal_sig_handler(int sig)
*/ */
call_exit_handlers(sig); call_exit_handlers(sig);
raise(sig); /* Workaround cached PID and TID races on glibc and Bionic libc. */
pid = syscall(SYS_getpid);
tid = syscall(SYS_gettid);
syscall(SYS_tgkill, pid, tid, sig);
} }
/* /*