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Yet another fix from BDE for the new pipe code. This fixes a potential

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deadlock due to mismanagement of busy counters.

Reviewed by: dyson
Submitted by: bde
This commit is contained in:
John Dyson 1996-03-17 04:52:10 +00:00
parent fe63158271
commit 7fe9c39bea
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=14644
1 changed files with 5 additions and 6 deletions
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11
sys/kern/sys_pipe.c
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@ -16,7 +16,7 @@
* 4. Modifications may be freely made to this file if the above conditions
* are met.
*
* $Id: sys_pipe.c,v 1.12 1996/02/17 14:47:16 peter Exp $
* $Id: sys_pipe.c,v 1.13 1996/02/22 03:33:52 dyson Exp $
*/
#ifndef OLD_PIPE
@ -759,13 +759,12 @@ pipewrite(wpipe, uio, nbio)
}
space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
/* Writes of size <= PIPE_BUF must be atomic. */
/* XXX perhaps they need to be contiguous to be atomic? */
if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
space = 0;
/*
* We must afford contiguous writes on buffers of size
* PIPE_BUF or less.
*/
if (space > 0) {
int size = wpipe->pipe_buffer.size - wpipe->pipe_buffer.in;
if (size > space)
@ -831,6 +830,7 @@ pipewrite(wpipe, uio, nbio)
}
}
--wpipe->pipe_busy;
if ((wpipe->pipe_busy == 0) &&
(wpipe->pipe_state & PIPE_WANT)) {
wpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTR);
@ -866,7 +866,6 @@ pipewrite(wpipe, uio, nbio)
if (wpipe->pipe_buffer.cnt)
pipeselwakeup(wpipe);
--wpipe->pipe_busy;
return error;
}