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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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