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Workaround to prevent a lockup in pipelock() in the case that signals are 

pending while we must wait for the lock.
This commit is contained in:
pk 2003-08-11 10:24:41 +00:00
parent 28d70b03dc
commit 9f987d0ac0
1 changed files with 20 additions and 2 deletions
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22
sys/kern/sys_pipe.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: sys_pipe.c,v 1.40 2003/06/29 22:31:26 fvdl Exp $ */
/* $NetBSD: sys_pipe.c,v 1.41 2003/08/11 10:24:41 pk Exp $ */
/*-
* Copyright (c) 2003 The NetBSD Foundation, Inc.
@ -83,7 +83,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.40 2003/06/29 22:31:26 fvdl Exp $");
__KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.41 2003/08/11 10:24:41 pk Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@ -358,6 +358,24 @@ pipelock(pipe, catch)
simple_lock(&pipe->pipe_slock);
if (catch || (error != EINTR && error != ERESTART))
break;
/*
* XXX XXX XXX
* The pipe lock is initialised with PCATCH on and we cannot
* override this in a lockmgr() call. Thus a pending signal
* will cause lockmgr() to return with EINTR or ERESTART.
* We cannot simply re-enter lockmgr() at this point since
* the pending signals have not yet been posted and would
* cause an immediate EINTR/ERESTART return again.
* As a workaround we pause for a while here, giving the lock
* a chance to drain, before trying again.
* XXX XXX XXX
*
* NOTE: Consider dropping PCATCH from this lock; in practice
* it is never held for long enough periods for having it
* interruptable at the start of pipe_read/pipe_write to be
* beneficial.
*/
(void) tsleep(&lbolt, PRIBIO, "rstrtpipelock", hz);
}
return (error);
}