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When the smbfs iod thread (smb_iod_thread()) is shutting down, smb_iod_destroy()

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would call smb_iod_request(). This call could return as soon as the
wakeup(evp) in smb_iod_main() call is done and then could destroy
the mutexes. This caused a race with the rest of smb_iod_main()s
use of these mutexes.
A crash reported on freebsd-stable@ by Christian Kratzer was
diagnosed as a use of one of these mutexes after it was destroyed.
This patch moves destruction of the mutexes from smb_iod_destroy()
to the end of smb_iod_thread(), so that they aren't destroyed before
the thread is done with them. Christian comfirmed that the patch
stopped the crashes from happening.

Reported by:	ck-lists@cksoft.de (Christian Kratzer)
Tested by:	ck-lists@cksoft.de (Christian Kratzer)
Diagnosed by:	jhb
Reviewed by:	jhb
MFC after:	2 weeks
This commit is contained in:
Rick Macklem 2015-11-16 23:19:53 +00:00
parent 7888a51f8d
commit e06f502c9e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=290959
1 changed files with 5 additions and 3 deletions
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8
sys/netsmb/smb_iod.c
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@ -659,6 +659,11 @@ smb_iod_thread(void *arg)
break;
tsleep(&iod->iod_flags, PWAIT, "90idle", iod->iod_sleeptimo);
}
/* We can now safely destroy the mutexes and free the iod structure. */
smb_sl_destroy(&iod->iod_rqlock);
smb_sl_destroy(&iod->iod_evlock);
free(iod, M_SMBIOD);
mtx_unlock(&Giant);
kproc_exit(0);
}
@ -695,9 +700,6 @@ int
smb_iod_destroy(struct smbiod *iod)
{
smb_iod_request(iod, SMBIOD_EV_SHUTDOWN | SMBIOD_EV_SYNC, NULL);
smb_sl_destroy(&iod->iod_rqlock);
smb_sl_destroy(&iod->iod_evlock);
free(iod, M_SMBIOD);
return 0;
}