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SubjectRe: [PATCH] tracing: allow tracing of suspend/resume & hibernation code again
Thanks Ingo,

I applied the patch (manually) agains Linus's git:

git describe
v2.6.28-rc6-7-ged31348

Previously, before the patch, I had no problem resuming - for
v2.6.28-rc6. Now after s2ram, it cannot resume properly - nothing is
displayed. And I had not applied any changes to ftrace's
/debug/tracing files yet.

Let me test it out again. Thanks. (I am on FC7).

On Sun, Nov 23, 2008 at 5:41 PM, Ingo Molnar <mingo@elte.hu> wrote:
>
> * Rafael J. Wysocki <rjw@sisk.pl> wrote:
>
>> > Q2: how to ftrace s2ram and resume? I attempted to do it, but the
>> > trace output is always filled with "resume" related functions when
>> > it started up, which is only logical.
>>
>> The tracing is disabled during suspend/resume, so you can't.
>
> i think we could lift this restriction now that dftrace is gone for
> good - which was causing most of the trouble.
>
> 41108eb10142e0552f2de1e4c0675b108c5f018f
> f42ac38c59e0a03d6da0c24a63fb211393f484b0
>
> Completely untested patch below. Peter, does it work for you?
>
> Ingo
>
> ------------------->
> From 3134c953216111a35d17f77b784e5d1fa2ba36d5 Mon Sep 17 00:00:00 2001
> From: Ingo Molnar <mingo@elte.hu>
> Date: Sun, 23 Nov 2008 10:37:12 +0100
> Subject: [PATCH] tracing: allow tracing of suspend/resume & hibernation code again:
>
> Now that the ftrace kernel thread is gone, we can allow tracing
> during suspend/resume again.
>
> So revert these two commits:
>
> f42ac38c5 "ftrace: disable tracing for suspend to ram"
> 41108eb10 "ftrace: disable tracing for hibernation"
>
> This should be tested very carefully, as it could interact with
> altneratives instruction patching, etc.
>
> Not-Yet-Signed-off-by: Ingo Molnar <mingo@elte.hu>
> ---
> kernel/power/disk.c | 13 +++----------
> kernel/power/main.c | 5 +----
> 2 files changed, 4 insertions(+), 14 deletions(-)
>
> diff --git a/kernel/power/disk.c b/kernel/power/disk.c
> index c9d7408..f77d381 100644
> --- a/kernel/power/disk.c
> +++ b/kernel/power/disk.c
> @@ -22,7 +22,6 @@
> #include <linux/console.h>
> #include <linux/cpu.h>
> #include <linux/freezer.h>
> -#include <linux/ftrace.h>
>
> #include "power.h"
>
> @@ -257,7 +256,7 @@ static int create_image(int platform_mode)
>
> int hibernation_snapshot(int platform_mode)
> {
> - int error, ftrace_save;
> + int error;
>
> /* Free memory before shutting down devices. */
> error = swsusp_shrink_memory();
> @@ -269,7 +268,6 @@ int hibernation_snapshot(int platform_mode)
> goto Close;
>
> suspend_console();
> - ftrace_save = __ftrace_enabled_save();
> error = device_suspend(PMSG_FREEZE);
> if (error)
> goto Recover_platform;
> @@ -299,7 +297,6 @@ int hibernation_snapshot(int platform_mode)
> Resume_devices:
> device_resume(in_suspend ?
> (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
> - __ftrace_enabled_restore(ftrace_save);
> resume_console();
> Close:
> platform_end(platform_mode);
> @@ -370,11 +367,10 @@ static int resume_target_kernel(void)
>
> int hibernation_restore(int platform_mode)
> {
> - int error, ftrace_save;
> + int error;
>
> pm_prepare_console();
> suspend_console();
> - ftrace_save = __ftrace_enabled_save();
> error = device_suspend(PMSG_QUIESCE);
> if (error)
> goto Finish;
> @@ -389,7 +385,6 @@ int hibernation_restore(int platform_mode)
> platform_restore_cleanup(platform_mode);
> device_resume(PMSG_RECOVER);
> Finish:
> - __ftrace_enabled_restore(ftrace_save);
> resume_console();
> pm_restore_console();
> return error;
> @@ -402,7 +397,7 @@ int hibernation_restore(int platform_mode)
>
> int hibernation_platform_enter(void)
> {
> - int error, ftrace_save;
> + int error;
>
> if (!hibernation_ops)
> return -ENOSYS;
> @@ -417,7 +412,6 @@ int hibernation_platform_enter(void)
> goto Close;
>
> suspend_console();
> - ftrace_save = __ftrace_enabled_save();
> error = device_suspend(PMSG_HIBERNATE);
> if (error) {
> if (hibernation_ops->recover)
> @@ -452,7 +446,6 @@ int hibernation_platform_enter(void)
> hibernation_ops->finish();
> Resume_devices:
> device_resume(PMSG_RESTORE);
> - __ftrace_enabled_restore(ftrace_save);
> resume_console();
> Close:
> hibernation_ops->end();
> diff --git a/kernel/power/main.c b/kernel/power/main.c
> index eaa122b..142e005 100644
> --- a/kernel/power/main.c
> +++ b/kernel/power/main.c
> @@ -22,7 +22,6 @@
> #include <linux/freezer.h>
> #include <linux/vmstat.h>
> #include <linux/syscalls.h>
> -#include <linux/ftrace.h>
>
> #include "power.h"
>
> @@ -321,7 +320,7 @@ static int suspend_enter(suspend_state_t state)
> */
> int suspend_devices_and_enter(suspend_state_t state)
> {
> - int error, ftrace_save;
> + int error;
>
> if (!suspend_ops)
> return -ENOSYS;
> @@ -332,7 +331,6 @@ int suspend_devices_and_enter(suspend_state_t state)
> goto Close;
> }
> suspend_console();
> - ftrace_save = __ftrace_enabled_save();
> suspend_test_start();
> error = device_suspend(PMSG_SUSPEND);
> if (error) {
> @@ -364,7 +362,6 @@ int suspend_devices_and_enter(suspend_state_t state)
> suspend_test_start();
> device_resume(PMSG_RESUME);
> suspend_test_finish("resume devices");
> - __ftrace_enabled_restore(ftrace_save);
> resume_console();
> Close:
> if (suspend_ops->end)
>



--
Regards,
Peter Teoh


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