linux-kernel - Re: [git pull] ftrace for v2.6.27

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Date:	Wed, 13 Aug 2008 13:15:14 -0400
From:	Steven Rostedt <srostedt@...hat.com>
To:	Bruce Duncan <bwduncan@...il.com>
CC:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	rostedt@...dmis.org
Subject: Re: [git pull] ftrace for v2.6.27

Bruce Duncan wrote:
> Hi Ingo, Steven, everyone,
>
> [ Please CC me in replies ]
>
> I have just tracked down a regression in 2.6.27-rc2 wrt 2.6.26. Commit 
> 77a2b37d227483fe52aead242652aee406c25bf0 (ftrace: startup tester on dynamic 
> tracing.) causes my laptop to fail to resume from S3 (it simply reboots about 
> a second after the resume starts and the display never shows anything).
>
> The patch doesn't revert with patch -R (I don't know if there's a cleverer way 
> to ask git to revert it), but the problem goes away if I turn off 
> CONFIG_DYNAMIC_FTRACE.
>
> The commit and bisect log are attached. Please can you help me to debug this?
>   
Hi Bruce,

Seems that the issue is with the "ftraced" daemon. The patch you 
reverted was just a fix in the ftrace startup test. If something fails 
in the start up test, that something is disabled.  There was a bug in 
the start up test that caused the dynamic ftrace to fail, and thus 
disabling dynamic ftrace. The patch you reverted, was the fix to that 
bug, so you indirectly disabled dynamic ftrace with that revert.

I've been developing a way to get rid of the "ftraced" daemon. Here's a 
big patch to do so against latest git (as of today). Can you go back to 
the original git, apply this patch and see if you can resume again.

After applying this patch you need to do a "chmod +x 
scripts/recordmcount.pl" before compiling.

Thanks,

-- Steve

Note: my goodmis.org account is currently offline :-( so I'm sending 
this from my redhat account, where I use TB. I have yet to figure out 
how to send a patch inline correctly with TB, so I'm attaching it.

View attachment "ftrace-mcount-record-big.patch" of type "text/x-patch" (19953 bytes)