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SubjectRe: [PATCH] ftrace: Disable function tracing during suspend/resume and hibernation, again
Date
On Monday, May 21, 2012, Srivatsa S. Bhat wrote:
> If function tracing is enabled for some of the low-level suspend/resume
> functions, it leads to triple fault during resume from suspend, ultimately
> ending up in a reboot instead of a resume (or a total refusal to come out
> of suspended state, on some machines).
>
> This issue was explained in more detail in commit f42ac38c59e0a03d (ftrace:
> disable tracing for suspend to ram). However, the changes made by that commit
> got reverted by commit cbe2f5a6e84eebb (tracing: allow tracing of
> suspend/resume & hibernation code again). So, unfortunately since things are
> not yet robust enough to allow tracing of low-level suspend/resume functions,
> suspend/resume is still broken when ftrace is enabled.
>
> So fix this by disabling function tracing during suspend/resume & hibernation.
>
> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
> Cc: stable@vger.kernel.org

Queued up for 3.6 in linux-pm/linux-next.

Thanks,
Rafael


> ---
>
> kernel/power/hibernate.c | 6 ++++++
> kernel/power/suspend.c | 3 +++
> 2 files changed, 9 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index e09dfbf..52a1817 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -352,6 +352,7 @@ int hibernation_snapshot(int platform_mode)
> }
>
> suspend_console();
> + ftrace_stop();
> pm_restrict_gfp_mask();
>
> error = dpm_suspend(PMSG_FREEZE);
> @@ -377,6 +378,7 @@ int hibernation_snapshot(int platform_mode)
> if (error || !in_suspend)
> pm_restore_gfp_mask();
>
> + ftrace_start();
> resume_console();
> dpm_complete(msg);
>
> @@ -479,6 +481,7 @@ int hibernation_restore(int platform_mode)
>
> pm_prepare_console();
> suspend_console();
> + ftrace_stop();
> pm_restrict_gfp_mask();
> error = dpm_suspend_start(PMSG_QUIESCE);
> if (!error) {
> @@ -486,6 +489,7 @@ int hibernation_restore(int platform_mode)
> dpm_resume_end(PMSG_RECOVER);
> }
> pm_restore_gfp_mask();
> + ftrace_start();
> resume_console();
> pm_restore_console();
> return error;
> @@ -512,6 +516,7 @@ int hibernation_platform_enter(void)
>
> entering_platform_hibernation = true;
> suspend_console();
> + ftrace_stop();
> error = dpm_suspend_start(PMSG_HIBERNATE);
> if (error) {
> if (hibernation_ops->recover)
> @@ -555,6 +560,7 @@ int hibernation_platform_enter(void)
> Resume_devices:
> entering_platform_hibernation = false;
> dpm_resume_end(PMSG_RESTORE);
> + ftrace_start();
> resume_console();
>
> Close:
> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
> index 396d262..c8b7446 100644
> --- a/kernel/power/suspend.c
> +++ b/kernel/power/suspend.c
> @@ -24,6 +24,7 @@
> #include <linux/export.h>
> #include <linux/suspend.h>
> #include <linux/syscore_ops.h>
> +#include <linux/ftrace.h>
> #include <trace/events/power.h>
>
> #include "power.h"
> @@ -212,6 +213,7 @@ int suspend_devices_and_enter(suspend_state_t state)
> goto Close;
> }
> suspend_console();
> + ftrace_stop();
> suspend_test_start();
> error = dpm_suspend_start(PMSG_SUSPEND);
> if (error) {
> @@ -231,6 +233,7 @@ int suspend_devices_and_enter(suspend_state_t state)
> suspend_test_start();
> dpm_resume_end(PMSG_RESUME);
> suspend_test_finish("resume devices");
> + ftrace_start();
> resume_console();
> Close:
> if (suspend_ops->end)
>
>
>



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