[Mesa-dev] [PATCH] gallium/util: Clarify comment in util_init_thread_pinning

Michel Dänzer michel at daenzer.net
Tue Sep 18 15:26:00 UTC 2018

From: Michel Dänzer <michel.daenzer at amd.com>

As discussed in the review of the patch which added the comment:

Nothing happens when a thread is created, because pthread_atfork doesn't
affect creating threads. However, spawning a child process will likely

Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
 src/gallium/auxiliary/util/u_helpers.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/gallium/auxiliary/util/u_helpers.c b/src/gallium/auxiliary/util/u_helpers.c
index b6cebf96329..4c70c004178 100644
--- a/src/gallium/auxiliary/util/u_helpers.c
+++ b/src/gallium/auxiliary/util/u_helpers.c
@@ -148,7 +148,10 @@ util_init_thread_pinning(void)
    /* Reset thread affinity for all child processes to prevent them from
     * inheriting the current thread's affinity.
-    * What happens if a driver is unloaded and the app creates a thread?
+    * XXX: If the driver is unloaded after this, and the app later calls
+    * fork(), the child process will likely crash before fork() returns,
+    * because the address where util_set_full_cpu_affinity was located
+    * will either be unmapped or point to random other contents.
    pthread_atfork(NULL, NULL, util_set_full_cpu_affinity);

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