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Subject[tip:tracing/core] x86, bts: use atomic memory allocation
Commit-ID:  c78a3956b982418186e40978a51636a2b43221bc
Gitweb: http://git.kernel.org/tip/c78a3956b982418186e40978a51636a2b43221bc
Author: Markus Metzger <markus.t.metzger@intel.com>
AuthorDate: Wed, 18 Mar 2009 19:27:00 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 19 Mar 2009 14:02:47 +0100

x86, bts: use atomic memory allocation

Ds_request_bts() needs to allocate memory. It uses GFP_KERNEL.

Hw-branch-tracer calls ds_request_bts() within on_each_cpu().

Use atomic memory allocation to allow it to be used in that context.

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
LKML-Reference: <20090318192700.A6038@sedona.ch.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
arch/x86/kernel/ds.c | 21 +++++++++++++++++----
1 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c
index 5fd5333..b1d6e1f 100644
--- a/arch/x86/kernel/ds.c
+++ b/arch/x86/kernel/ds.c
@@ -255,8 +255,13 @@ static inline struct ds_context *ds_get_context(struct task_struct *task)
struct ds_context *new_context = NULL;
unsigned long irq;

- /* Chances are small that we already have a context. */
- new_context = kzalloc(sizeof(*new_context), GFP_KERNEL);
+ /*
+ * Chances are small that we already have a context.
+ *
+ * Contexts for per-cpu tracing are allocated using
+ * smp_call_function(). We must not sleep.
+ */
+ new_context = kzalloc(sizeof(*new_context), GFP_ATOMIC);
if (!new_context)
return NULL;

@@ -662,8 +667,12 @@ struct bts_tracer *ds_request_bts(struct task_struct *task,
if (ovfl)
goto out;

+ /*
+ * Per-cpu tracing is typically requested using smp_call_function().
+ * We must not sleep.
+ */
error = -ENOMEM;
- tracer = kzalloc(sizeof(*tracer), GFP_KERNEL);
+ tracer = kzalloc(sizeof(*tracer), GFP_ATOMIC);
if (!tracer)
goto out;
tracer->ovfl = ovfl;
@@ -722,8 +731,12 @@ struct pebs_tracer *ds_request_pebs(struct task_struct *task,
if (ovfl)
goto out;

+ /*
+ * Per-cpu tracing is typically requested using smp_call_function().
+ * We must not sleep.
+ */
error = -ENOMEM;
- tracer = kzalloc(sizeof(*tracer), GFP_KERNEL);
+ tracer = kzalloc(sizeof(*tracer), GFP_ATOMIC);
if (!tracer)
goto out;
tracer->ovfl = ovfl;

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