Patchwork [Lucid-ec2] SRU: XEN: Do not force sched_clock_stable

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Submitter Stefan Bader
Date May 17, 2011, 5:29 p.m.
Message ID <1305653374-2163-1-git-send-email-stefan.bader@canonical.com>
Download mbox | patch
Permalink /patch/96002/
State New
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Comments

Stefan Bader - May 17, 2011, 5:29 p.m.
SRU Justification

Impact: When applying the Xen patchset one endif seems to have gone to
the wrong place. So instead of not setting sched_clock_stable it is done
all the time.

Fix: Move endif so the whole code segment is covered.

Testcase: Can cause various effects and depends on CPU (see below).
Incorrect CPU time but likely also causing the unexplainable process
gets stuck or clone/fork issues.

---

From 5f1bda076198807960d023c4d1551485c8d77ef5 Mon Sep 17 00:00:00 2001
From: Stefan Bader <stefan.bader@canonical.com>
Date: Tue, 17 May 2011 19:16:30 +0200
Subject: [PATCH] UBUNTU: SAUCE: XEN: Do not force sched_clock_stable

BugLink: http://bugs.launchpad.net/bugs/727459

This is part of the changes that have been found while syncing up
the patchsets. Apparently when applying the endif went into the
wrong place and causes the clock to be assumed always stable. Which
causes problems on certain CPUs (probably the fork/clone hang as well
as processes getting stuck for a longer time).

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
---
 arch/x86/kernel/cpu/intel.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
Leann Ogasawara - May 17, 2011, 6:54 p.m.
On Tue, 2011-05-17 at 19:29 +0200, Stefan Bader wrote:
> SRU Justification
> 
> Impact: When applying the Xen patchset one endif seems to have gone to
> the wrong place. So instead of not setting sched_clock_stable it is done
> all the time.
> 
> Fix: Move endif so the whole code segment is covered.
> 
> Testcase: Can cause various effects and depends on CPU (see below).
> Incorrect CPU time but likely also causing the unexplainable process
> gets stuck or clone/fork issues.
> 
> ---
> 
> From 5f1bda076198807960d023c4d1551485c8d77ef5 Mon Sep 17 00:00:00 2001
> From: Stefan Bader <stefan.bader@canonical.com>
> Date: Tue, 17 May 2011 19:16:30 +0200
> Subject: [PATCH] UBUNTU: SAUCE: XEN: Do not force sched_clock_stable
> 
> BugLink: http://bugs.launchpad.net/bugs/727459
> 
> This is part of the changes that have been found while syncing up
> the patchsets. Apparently when applying the endif went into the
> wrong place and causes the clock to be assumed always stable. Which
> causes problems on certain CPUs (probably the fork/clone hang as well
> as processes getting stuck for a longer time).
> 
> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Acked-by: Leann Ogasawara <leann.ogasawara@canonical.com>

> ---
>  arch/x86/kernel/cpu/intel.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
> index 0aad121..f582b21 100644
> --- a/arch/x86/kernel/cpu/intel.c
> +++ b/arch/x86/kernel/cpu/intel.c
> @@ -97,8 +97,8 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c)
>  		set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC);
>  #ifndef CONFIG_XEN
>  		if (!check_tsc_unstable())
> -#endif
>  			sched_clock_stable = 1;
> +#endif
>  	}
>  
>  	/*
> -- 
> 1.7.0.4
> 
>
John Johansen - May 17, 2011, 7:28 p.m.
On 05/17/2011 10:29 AM, Stefan Bader wrote:
> SRU Justification
> 
> Impact: When applying the Xen patchset one endif seems to have gone to
> the wrong place. So instead of not setting sched_clock_stable it is done
> all the time.
> 
> Fix: Move endif so the whole code segment is covered.
> 
> Testcase: Can cause various effects and depends on CPU (see below).
> Incorrect CPU time but likely also causing the unexplainable process
> gets stuck or clone/fork issues.
> 
> ---
> 
> From 5f1bda076198807960d023c4d1551485c8d77ef5 Mon Sep 17 00:00:00 2001
> From: Stefan Bader <stefan.bader@canonical.com>
> Date: Tue, 17 May 2011 19:16:30 +0200
> Subject: [PATCH] UBUNTU: SAUCE: XEN: Do not force sched_clock_stable
> 
> BugLink: http://bugs.launchpad.net/bugs/727459
> 
> This is part of the changes that have been found while syncing up
> the patchsets. Apparently when applying the endif went into the
> wrong place and causes the clock to be assumed always stable. Which
> causes problems on certain CPUs (probably the fork/clone hang as well
> as processes getting stuck for a longer time).
> 
> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: John Johansen <john.johansen@canonical.com>

> ---
>  arch/x86/kernel/cpu/intel.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
> index 0aad121..f582b21 100644
> --- a/arch/x86/kernel/cpu/intel.c
> +++ b/arch/x86/kernel/cpu/intel.c
> @@ -97,8 +97,8 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c)
>  		set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC);
>  #ifndef CONFIG_XEN
>  		if (!check_tsc_unstable())
> -#endif
>  			sched_clock_stable = 1;
> +#endif
>  	}
>  
>  	/*
Stefan Bader - May 18, 2011, 7:15 a.m.
Applied and pushed to lucid-ec2

Patch

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 0aad121..f582b21 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -97,8 +97,8 @@  static void __cpuinit early_init_intel(struct cpuinfo_x86 *c)
 		set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC);
 #ifndef CONFIG_XEN
 		if (!check_tsc_unstable())
-#endif
 			sched_clock_stable = 1;
+#endif
 	}
 
 	/*