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just use ltsleep rather than lockmgr + PCATCH with horrible timeout dance.

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This commit is contained in:
yamt 2005-10-29 12:31:07 +00:00
parent c14bdacc17
commit dd80ddaf14
2 changed files with 29 additions and 36 deletions
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58
sys/kern/sys_pipe.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: sys_pipe.c,v 1.66 2005/09/11 17:55:26 christos Exp $ */
/* $NetBSD: sys_pipe.c,v 1.67 2005/10/29 12:31:07 yamt Exp $ */
/*-
* Copyright (c) 2003 The NetBSD Foundation, Inc.
@ -83,7 +83,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.66 2005/09/11 17:55:26 christos Exp $");
__KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.67 2005/10/29 12:31:07 yamt Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@ -324,7 +324,6 @@ pipe_create(pipep, allockva)
pipe->pipe_atime = pipe->pipe_ctime;
pipe->pipe_mtime = pipe->pipe_ctime;
simple_lock_init(&pipe->pipe_slock);
lockinit(&pipe->pipe_lock, PSOCK | PCATCH, "pipelk", 0, 0);
if (allockva && (error = pipespace(pipe, PIPE_SIZE)))
return (error);
@ -343,40 +342,24 @@ pipelock(pipe, catch)
struct pipe *pipe;
int catch;
{
int error;
LOCK_ASSERT(simple_lock_held(&pipe->pipe_slock));
while (1) {
error = lockmgr(&pipe->pipe_lock, LK_EXCLUSIVE | LK_INTERLOCK,
&pipe->pipe_slock);
if (error == 0)
break;
while (pipe->pipe_state & PIPE_LOCKFL) {
int error;
const int pcatch = catch ? PCATCH : 0;
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) ltsleep(&lbolt, PSOCK, "rstrtpipelock", hz,
pipe->pipe_state |= PIPE_LWANT;
error = ltsleep(pipe, PSOCK | pcatch, "pipelk", 0,
&pipe->pipe_slock);
if (error != 0)
return error;
}
return (error);
pipe->pipe_state |= PIPE_LOCKFL;
simple_unlock(&pipe->pipe_slock);
return 0;
}
/*
@ -387,7 +370,13 @@ pipeunlock(pipe)
struct pipe *pipe;
{
lockmgr(&pipe->pipe_lock, LK_RELEASE, NULL);
KASSERT(pipe->pipe_state & PIPE_LOCKFL);
pipe->pipe_state &= ~PIPE_LOCKFL;
if (pipe->pipe_state & PIPE_LWANT) {
pipe->pipe_state &= ~PIPE_LWANT;
wakeup(pipe);
}
}
/*
@ -1352,8 +1341,9 @@ retry:
PIPE_UNLOCK(ppipe);
}
(void)lockmgr(&pipe->pipe_lock, LK_DRAIN | LK_INTERLOCK,
&pipe->pipe_slock);
KASSERT((pipe->pipe_state & PIPE_LOCKFL) == 0);
PIPE_UNLOCK(pipe);
/*
* free resources

7
sys/sys/pipe.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: pipe.h,v 1.16 2005/03/17 20:39:17 kleink Exp $ */
/* $NetBSD: pipe.h,v 1.17 2005/10/29 12:31:07 yamt Exp $ */
/*
* Copyright (c) 1996 John S. Dyson
@ -94,6 +94,10 @@ struct pipemapping {
#define PIPE_SIGNALR 0x020 /* Do selwakeup() on read(2) */
#define PIPE_DIRECTW 0x040 /* Pipe in direct write mode setup */
#define PIPE_DIRECTR 0x080 /* Pipe direct read request (setup complete) */
#define PIPE_LOCKFL 0x100 /* Process has exclusive access to
pointers/data. */
#define PIPE_LWANT 0x200 /* Process wants exclusive access to
pointers/data. */
/*
* Per-pipe data structure.
@ -101,7 +105,6 @@ struct pipemapping {
*/
struct pipe {
struct simplelock pipe_slock; /* pipe mutex */
struct lock pipe_lock; /* long-term pipe lock */
struct pipebuf pipe_buffer; /* data storage */
struct pipemapping pipe_map; /* pipe mapping for direct I/O */
struct selinfo pipe_sel; /* for compat with select */