[PATCH] Fix sporadic XFAILs in, gdb.threads/attach-many-short-lived-threads.exp
Bernd Edlinger
bernd.edlinger@hotmail.de
Sun Mar 31 10:47:24 GMT 2024
This is about random test failures like those:
XFAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 6: attach (EPERM)
XFAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 7: attach (EPERM)
XFAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 8: attach (EPERM)
XFAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 9: attach (EPERM)
XFAIL: gdb.threads/attach-many-short-lived-threads.exp: iter 10: attach (EPERM)
The reason for this effect is apparently as follows:
There is a race condition when gdb tries to attach a thread but the
thread exits at the same time. Normally when that happens the return
code of ptrace(PTRACE_ATTACH, x) is EPERM, which could also have other
reasons. To detect the true reason, we try to open /proc/<pid>/status
which normally fails in that situation, but it may happen that the
fopen succeeds, and the thread disappears while reading the content,
then the read has the errno=ESRCH, use that as an indication that the
thread has exited between fopen and reading of the status file.
---
gdb/nat/linux-procfs.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/gdb/nat/linux-procfs.c b/gdb/nat/linux-procfs.c
index e2086952ce6..36e0f5bf16a 100644
--- a/gdb/nat/linux-procfs.c
+++ b/gdb/nat/linux-procfs.c
@@ -165,6 +165,9 @@ linux_proc_pid_is_gone (pid_t pid)
}
else if (have_state == 0)
{
+ /* errno is ESRCH "No such process": assume thread has disappeared. */
+ if (errno == ESRCH)
+ return 1;
/* No "State:" line, assume thread is alive. */
return 0;
}
--
2.39.2
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