Re: [PATCH] microblaze: Fix ftrace_update_ftrace_func panic

From: Michal Simek
Date: Tue Apr 06 2010 - 02:29:31 EST

Steven J. Magnani wrote:
On Mon, 2010-04-05 at 16:26 +0200, Michal Simek wrote:
Steven J. Magnani wrote:
The Microblaze dynamic ftrace code assumes a call ordering that is not met
in all scenarios. Specifically, executing a command similar to:

echo 105 > /sys/kernel/debug/tracing/set_ftrace_pid

before any other tracing-related commands results in a kernel panic:

BUG: failure at arch/microblaze/kernel/ftrace.c:198/ftrace_update_ftrace_func()!

Recoding ftrace_update_ftrace_func() to use &ftrace_caller directly eliminates the need to capture its address elsewhere (and thus rely on a particular call sequence).
I would like to replicate this problem to see that there is. I am not able to reach this fault
Please copy & paste log with your commands.

# echo 80 > /sys/kernel/debug/tracing/set_ftrace_pid
BUG: failure at
Kernel panic - not syncing: BUG!

I am able to replicate this fault on both versions.
Added to next branch.


Michal Simek, Ing. (M.Eng)
w: p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux -
Microblaze U-BOOT custodian
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