4.14 stable missing 3054426dc68e "sched, trace: Fix prev_state output in sched_switch tracepoint"

4.14 stable missing 3054426dc68e "sched, trace: Fix prev_state output in sched_switch tracepoint"

[Chris Redpath]

Hi Greg et al.

A user of android-4.14 has pointed the following missing commit out.

Commit 3054426dc68e ("sched, trace: Fix prev_state output in sched_switch tracepoint") was put into linux-4.20 around rc5 to fix an issue in a tracepoint. According to the patch itself, the broken commit was 3f5fe9fef5b2 ("sched/debug: Fix task state recording/printout") which was merged at what looks like 4.15-rc2. The broken commit was also picked for 4.14.64 as 13f12749af15 ("sched/debug: Fix task state recording/printout"). The fix (3054426dc68e) was pulled into 4.19. but was not called out as needing to go back to 4.14.

Is it possible to pick 3054426dc68e ("sched, trace: Fix prev_state output in sched_switch tracepoint") for the next stable 4.14 release? If not I can do a backport for android-4.14, just let me know.

Best Regards,
Chris

Re: 4.14 stable missing 3054426dc68e "sched, trace: Fix prev_state output in sched_switch tracepoint"

[Sasha Levin]

On Fri, Feb 15, 2019 at 12:26:35PM +0000, Chris Redpath wrote:
>Hi Greg et al.
>
>A user of android-4.14 has pointed the following missing commit out.
>
>Commit 3054426dc68e ("sched, trace: Fix prev_state output in sched_switch tracepoint") was put into linux-4.20 around rc5 to fix an issue in a tracepoint. According to the patch itself, the broken commit was 3f5fe9fef5b2 ("sched/debug: Fix task state recording/printout") which was merged at what looks like 4.15-rc2. The broken commit was also picked for 4.14.64 as 13f12749af15 ("sched/debug: Fix task state recording/printout"). The fix (3054426dc68e) was pulled into 4.19. but was not called out as needing to go back to 4.14.
>
>Is it possible to pick 3054426dc68e ("sched, trace: Fix prev_state output in sched_switch tracepoint") for the next stable 4.14 release? If not I can do a backport for android-4.14, just let me know.

It wasn't backported because it didn't apply cleanly, since 4.4's
backport of 3f5fe9fef5b2 differs from Linus's tree.

The backport for that commit was done by Sudip (Cc'ed). I'll be happy to
take a backport of 3054426dc68e if someone sense one my way.

--
Thanks,
Sasha

Re: 4.14 stable missing 3054426dc68e "sched, trace: Fix prev_state output in sched_switch tracepoint"

[Sudip Mukherjee]

[-- Attachment #1: Type: text/plain, Size: 1481 bytes --]

Hi Sasha,

On Sun, Feb 17, 2019 at 09:06:36PM -0500, Sasha Levin wrote:
> On Fri, Feb 15, 2019 at 12:26:35PM +0000, Chris Redpath wrote:
> > Hi Greg et al.
> > 
> > A user of android-4.14 has pointed the following missing commit out.
> > 
> > Commit 3054426dc68e ("sched, trace: Fix prev_state output in sched_switch tracepoint") was put into linux-4.20 around rc5 to fix an issue in a tracepoint. According to the patch itself, the broken commit was 3f5fe9fef5b2 ("sched/debug: Fix task state recording/printout") which was merged at what looks like 4.15-rc2. The broken commit was also picked for 4.14.64 as 13f12749af15 ("sched/debug: Fix task state recording/printout"). The fix (3054426dc68e) was pulled into 4.19. but was not called out as needing to go back to 4.14.
> > 
> > Is it possible to pick 3054426dc68e ("sched, trace: Fix prev_state output in sched_switch tracepoint") for the next stable 4.14 release? If not I can do a backport for android-4.14, just let me know.
> 
> It wasn't backported because it didn't apply cleanly, since 4.4's
> backport of 3f5fe9fef5b2 differs from Linus's tree.
> 
> The backport for that commit was done by Sudip (Cc'ed). I'll be happy to
> take a backport of 3054426dc68e if someone sense one my way.

Happy to do a backport for 4.14-stable. :)

It did not apply before as the function was only renamed by:
1d48b080bcce ("sched/debug: Rename task-state printing helpers")

There was no other functionality change.


--
Regards
Sudip

[-- Attachment #2: 0001-sched-trace-Fix-prev_state-output-in-sched_switch-tr.patch --]
[-- Type: text/x-diff, Size: 2277 bytes --]

From f8c12fb36c1164fbd1ffaabd9898dfb2af1ee28a Mon Sep 17 00:00:00 2001
From: Pavankumar Kondeti <pkondeti@codeaurora.org>
Date: Tue, 30 Oct 2018 12:24:33 +0530
Subject: [PATCH] sched, trace: Fix prev_state output in sched_switch tracepoint

commit 3054426dc68e5d63aa6a6e9b91ac4ec78e3f3805 upstream

commit 3f5fe9fef5b2 ("sched/debug: Fix task state recording/printout")
tried to fix the problem introduced by a previous commit efb40f588b43
("sched/tracing: Fix trace_sched_switch task-state printing"). However
the prev_state output in sched_switch is still broken.

task_state_index() uses fls() which considers the LSB as 1. Left
shifting 1 by this value gives an incorrect mapping to the task state.
Fix this by decrementing the value returned by __get_task_state()
before shifting.

Link: http://lkml.kernel.org/r/1540882473-1103-1-git-send-email-pkondeti@codeaurora.org

Cc: stable@vger.kernel.org
Fixes: 3f5fe9fef5b2 ("sched/debug: Fix task state recording/printout")
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
---
 include/trace/events/sched.h | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 0812cd5408c9..6e692a52936c 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -107,6 +107,8 @@ DEFINE_EVENT(sched_wakeup_template, sched_wakeup_new,
 #ifdef CREATE_TRACE_POINTS
 static inline long __trace_sched_switch_state(bool preempt, struct task_struct *p)
 {
+	unsigned int state;
+
 #ifdef CONFIG_SCHED_DEBUG
 	BUG_ON(p != current);
 #endif /* CONFIG_SCHED_DEBUG */
@@ -118,7 +120,15 @@ static inline long __trace_sched_switch_state(bool preempt, struct task_struct *
 	if (preempt)
 		return TASK_REPORT_MAX;
 
-	return 1 << __get_task_state(p);
+	/*
+	 * task_state_index() uses fls() and returns a value from 0-8 range.
+	 * Decrement it by 1 (except TASK_RUNNING state i.e 0) before using
+	 * it for left shift operation to get the correct task->state
+	 * mapping.
+	 */
+	state = __get_task_state(p);
+
+	return state ? (1 << (state - 1)) : state;
 }
 #endif /* CREATE_TRACE_POINTS */
 
-- 
2.11.0

Re: 4.14 stable missing 3054426dc68e "sched, trace: Fix prev_state output in sched_switch tracepoint"

[Greg KH]

On Mon, Feb 18, 2019 at 09:14:03AM +0000, Sudip Mukherjee wrote:
> Hi Sasha,
> 
> On Sun, Feb 17, 2019 at 09:06:36PM -0500, Sasha Levin wrote:
> > On Fri, Feb 15, 2019 at 12:26:35PM +0000, Chris Redpath wrote:
> > > Hi Greg et al.
> > > 
> > > A user of android-4.14 has pointed the following missing commit out.
> > > 
> > > Commit 3054426dc68e ("sched, trace: Fix prev_state output in sched_switch tracepoint") was put into linux-4.20 around rc5 to fix an issue in a tracepoint. According to the patch itself, the broken commit was 3f5fe9fef5b2 ("sched/debug: Fix task state recording/printout") which was merged at what looks like 4.15-rc2. The broken commit was also picked for 4.14.64 as 13f12749af15 ("sched/debug: Fix task state recording/printout"). The fix (3054426dc68e) was pulled into 4.19. but was not called out as needing to go back to 4.14.
> > > 
> > > Is it possible to pick 3054426dc68e ("sched, trace: Fix prev_state output in sched_switch tracepoint") for the next stable 4.14 release? If not I can do a backport for android-4.14, just let me know.
> > 
> > It wasn't backported because it didn't apply cleanly, since 4.4's
> > backport of 3f5fe9fef5b2 differs from Linus's tree.
> > 
> > The backport for that commit was done by Sudip (Cc'ed). I'll be happy to
> > take a backport of 3054426dc68e if someone sense one my way.
> 
> Happy to do a backport for 4.14-stable. :)
> 
> It did not apply before as the function was only renamed by:
> 1d48b080bcce ("sched/debug: Rename task-state printing helpers")
> 
> There was no other functionality change.

Now queued up, thanks.

greg k-h

Re: 4.14 stable missing 3054426dc68e "sched, trace: Fix prev_state output in sched_switch tracepoint"

[Chris Redpath]

On 18/02/2019 12:19, Greg KH wrote:
> On Mon, Feb 18, 2019 at 09:14:03AM +0000, Sudip Mukherjee wrote:
>> Hi Sasha,
>>
>> On Sun, Feb 17, 2019 at 09:06:36PM -0500, Sasha Levin wrote:
>>> On Fri, Feb 15, 2019 at 12:26:35PM +0000, Chris Redpath wrote:
>>>> Hi Greg et al.
>>>>
>>>> A user of android-4.14 has pointed the following missing commit out.
>>>>
>>>> Commit 3054426dc68e ("sched, trace: Fix prev_state output in sched_switch tracepoint") was put into linux-4.20 around rc5 to fix an issue in a tracepoint. According to the patch itself, the broken commit was 3f5fe9fef5b2 ("sched/debug: Fix task state recording/printout") which was merged at what looks like 4.15-rc2. The broken commit was also picked for 4.14.64 as 13f12749af15 ("sched/debug: Fix task state recording/printout"). The fix (3054426dc68e) was pulled into 4.19. but was not called out as needing to go back to 4.14.
>>>>
>>>> Is it possible to pick 3054426dc68e ("sched, trace: Fix prev_state output in sched_switch tracepoint") for the next stable 4.14 release? If not I can do a backport for android-4.14, just let me know.
>>>
>>> It wasn't backported because it didn't apply cleanly, since 4.4's
>>> backport of 3f5fe9fef5b2 differs from Linus's tree.
>>>
>>> The backport for that commit was done by Sudip (Cc'ed). I'll be happy to
>>> take a backport of 3054426dc68e if someone sense one my way.
>>
>> Happy to do a backport for 4.14-stable. :)
>>
>> It did not apply before as the function was only renamed by:
>> 1d48b080bcce ("sched/debug: Rename task-state printing helpers")
>>
>> There was no other functionality change.
> 
> Now queued up, thanks.
> 
> greg k-h
> 
Thanks everyone, much appreciated!
--Chris