Custom dump path #5
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
Nice. Thanks! |
XrXr
added a commit
to XrXr/stackprof
that referenced
this pull request
Dec 10, 2024
I got a SEGV core dump with the stack trace as follows:
#0 __pthread_kill_implementation (no_tid=0, signo=14, threadid=0) at ./nptl/pthread_kill.c:50
tmm1#1 __pthread_kill_internal (signo=14, threadid=0) at ./nptl/pthread_kill.c:78
tmm1#2 __GI___pthread_kill (threadid=0, signo=14) at ./nptl/pthread_kill.c:89
tmm1#3 <signal handler called> () at /lib/x86_64-linux-gnu/libc.so.6
tmm1#4 stackprof_start (argc=<optimized out>, argv=<optimized out>, self=<optimized out>) at stackprof.c:228
tmm1#5 vm_call_cfunc_with_frame_
...
Notice that `threadid=0` in the top frame -- the SEGV comes from inside
libc as it tries to dereference `threadid`.
The signal comes from stackprof's signal handler:
if (pthread_self() != _stackprof.target_thread) {
pthread_kill(_stackprof.target_thread, sig);
return;
}
During stackprof_start(), `_stackprof.target_thread` is 0.
You can recreate the stack trace in the crash with a program that does
`pthread_kill(0, SIGALRM)`:
#include <signal.h>
int
main(void)
{
pthread_kill(0, SIGALRM);
}
Only set `running` after target_thread is set to avoid this crash in
case the timer expires after `settimer()` but before setting
`target_thread`.
Also, since the ordering is important here, make `running`
`volatile sig_atomic_t` to prevent the compiler from doing unwanted
reordering.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Add ability to set custom dump path for middleware.