Module Name: src
Committed By: hannken
Date: Sat Oct 2 07:35:41 UTC 2021
Modified Files:
src/sys/kern: sys_pipe.c
Log Message:
Fix a deadlock where one thread writes to a pipe, has more data
and no space in the pipe and waits on "pipe_wcv" while the reader
is closing the pipe and waits on "pipe_draincv".
Swap the test for "PIPE_EOF" and the "cv_wait_sig()" in "pipe_write()".
PR bin/56422 "zgrep -l sometimes hangs"
To generate a diff of this commit:
cvs rdiff -u -r1.156 -r1.157 src/sys/kern/sys_pipe.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/sys_pipe.c
diff -u src/sys/kern/sys_pipe.c:1.156 src/sys/kern/sys_pipe.c:1.157
--- src/sys/kern/sys_pipe.c:1.156 Mon Sep 27 00:51:10 2021
+++ src/sys/kern/sys_pipe.c Sat Oct 2 07:35:40 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: sys_pipe.c,v 1.156 2021/09/27 00:51:10 thorpej Exp $ */
+/* $NetBSD: sys_pipe.c,v 1.157 2021/10/02 07:35:40 hannken Exp $ */
/*-
* Copyright (c) 2003, 2007, 2008, 2009 The NetBSD Foundation, Inc.
@@ -68,7 +68,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.156 2021/09/27 00:51:10 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.157 2021/10/02 07:35:40 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -694,11 +694,6 @@ pipe_write(file_t *fp, off_t *offset, st
break;
}
- pipeunlock(wpipe);
- error = cv_wait_sig(&wpipe->pipe_wcv, lock);
- (void)pipelock(wpipe, false);
- if (error != 0)
- break;
/*
* If read side wants to go away, we just issue a signal
* to ourselves.
@@ -707,6 +702,12 @@ pipe_write(file_t *fp, off_t *offset, st
error = EPIPE;
break;
}
+
+ pipeunlock(wpipe);
+ error = cv_wait_sig(&wpipe->pipe_wcv, lock);
+ (void)pipelock(wpipe, false);
+ if (error != 0)
+ break;
wakeup_state = wpipe->pipe_state;
}
}
