upstream/opnsense-src
1
0
Fork 0
mirror of https://github.com/opnsense/src.git synced 2026-06-09 00:32:25 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

libprocstat kstack: fix race with thread creation

Browse source 
When collecting kernel stacks for a target process, if the process
adds a thread between the two calls to sysctl, ignore the additional
threads.  Previously, procstat would print only a useless error
message.  Now, it prints a consistent snapshot of the stacks.
We know that snapshot is already stale, but it could still be stale
even with a more complex fix to reallocate and retry, so such a fix
is hardly worth the effort.

Reported by:	Daniel.Mitchell@emc.com
MFC after:	1 week
Sponsored by:	Dell EMC Isilon

(cherry picked from commit 427f12f150)
This commit is contained in:
Eric van Gyzen 2021-05-27 11:33:22 -05:00
parent 94df301ac2
commit d895236443
1 changed files with 2 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
lib/libprocstat/libprocstat.c
View file

@ -2610,7 +2610,8 @@ procstat_getkstack_sysctl(pid_t pid, int *cntp)
warn("malloc(%zu)", len);
return (NULL);
}
if (sysctl(name, nitems(name), kkstp, &len, NULL, 0) == -1) {
if (sysctl(name, nitems(name), kkstp, &len, NULL, 0) == -1 &&
errno != ENOMEM) {
warn("sysctl: kern.proc.pid: %d", pid);
free(kkstp);
return (NULL);