linux-kernel - RE: which signal is sent to freeze process?

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Message-ID: <A3258B497F1C1441AD36A2E8B45FD62858D6A0@scsmsx412.amr.corp.intel.com>
Date:	Mon, 23 Jul 2007 13:57:35 -0700
From:	"Agarwal, Lomesh" <lomesh.agarwal@...el.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	<nigel@...pend2.net>, <linux-kernel@...r.kernel.org>
Subject: RE: which signal is sent to freeze process?

Why do you need try_to_freeze in below patch? Shouldn't
!freezing(current) checking is enough?

-----Original Message-----
From: Rafael J. Wysocki [mailto:rjw@...k.pl] 
Sent: Friday, July 20, 2007 3:10 PM
To: Agarwal, Lomesh
Cc: nigel@...pend2.net; linux-kernel@...r.kernel.org
Subject: Re: which signal is sent to freeze process?

On Friday, 20 July 2007 20:07, Agarwal, Lomesh wrote:
> Can you suggest a way I can debug the issue why I am getting EINTR
error
> for system calls in resuming? What else can cause the system call
> failure with EINTR?

Well, I think I know what the problem is.  do_poll checks
signal_pending(current) and breaks when it's set, but that may be caused
by the freezer.

You may try the patch below (untested) and see if that helps.

Greetings,
Rafael


---
 fs/select.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Index: linux-2.6.22-rc6-mm1/fs/select.c
===================================================================
--- linux-2.6.22-rc6-mm1.orig/fs/select.c
+++ linux-2.6.22-rc6-mm1/fs/select.c
@@ -23,6 +23,7 @@
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/rcupdate.h>
+#include <linux/freezer.h>
 
 #include <asm/uaccess.h>
 
@@ -593,6 +594,8 @@ static int do_poll(unsigned int nfds,  s
 		struct poll_list *walk;
 		long __timeout;
 
+		try_to_freeze();
+
 		set_current_state(TASK_INTERRUPTIBLE);
 		for (walk = list; walk != NULL; walk = walk->next) {
 			struct pollfd * pfd, * pfd_end;
@@ -618,7 +621,8 @@ static int do_poll(unsigned int nfds,  s
 		 * a poll_table to them on the next loop iteration.
 		 */
 		pt = NULL;
-		if (count || !*timeout || signal_pending(current))
+		if (count || !*timeout ||
+		    (signal_pending(current) && !freezing(current)))
 			break;
 		count = wait->error;
 		if (count)
-
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