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    Subject[tip:perf/core] percpu: Add __percpu sparse annotations to hw_breakpoint
    Commit-ID:  44ee63587dce85593c22497140db16f4e5027860
    Gitweb: http://git.kernel.org/tip/44ee63587dce85593c22497140db16f4e5027860
    Author: Tejun Heo <tj@kernel.org>
    AuthorDate: Wed, 17 Feb 2010 10:50:50 +0900
    Committer: Frederic Weisbecker <fweisbec@gmail.com>
    CommitDate: Sat, 27 Feb 2010 16:23:39 +0100

    percpu: Add __percpu sparse annotations to hw_breakpoint

    Add __percpu sparse annotations to hw_breakpoint.

    These annotations are to make sparse consider percpu variables to be
    in a different address space and warn if accessed without going
    through percpu accessors. This patch doesn't affect normal builds.

    In kernel/hw_breakpoint.c, per_cpu(nr_task_bp_pinned, cpu)'s will
    trigger spurious noderef related warnings from sparse. Changing it to
    &per_cpu(nr_task_bp_pinned[0], cpu) will work around the problem but
    deemed to ugly by the maintainer. Leave it alone until better
    solution can be found.

    Signed-off-by: Tejun Heo <tj@kernel.org>
    Cc: Stephen Rothwell <sfr@canb.auug.org.au>
    Cc: K.Prasad <prasad@linux.vnet.ibm.com>
    LKML-Reference: <4B7B4B7A.9050902@kernel.org>
    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
    ---
    include/linux/hw_breakpoint.h | 8 ++++----
    kernel/hw_breakpoint.c | 10 +++++-----
    samples/hw_breakpoint/data_breakpoint.c | 6 +++---
    3 files changed, 12 insertions(+), 12 deletions(-)

    diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
    index 5977b72..c70d27a 100644
    --- a/include/linux/hw_breakpoint.h
    +++ b/include/linux/hw_breakpoint.h
    @@ -66,14 +66,14 @@ register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,
    perf_overflow_handler_t triggered,
    int cpu);

    -extern struct perf_event **
    +extern struct perf_event * __percpu *
    register_wide_hw_breakpoint(struct perf_event_attr *attr,
    perf_overflow_handler_t triggered);

    extern int register_perf_hw_breakpoint(struct perf_event *bp);
    extern int __register_perf_hw_breakpoint(struct perf_event *bp);
    extern void unregister_hw_breakpoint(struct perf_event *bp);
    -extern void unregister_wide_hw_breakpoint(struct perf_event **cpu_events);
    +extern void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events);

    extern int dbg_reserve_bp_slot(struct perf_event *bp);
    extern int dbg_release_bp_slot(struct perf_event *bp);
    @@ -100,7 +100,7 @@ static inline struct perf_event *
    register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,
    perf_overflow_handler_t triggered,
    int cpu) { return NULL; }
    -static inline struct perf_event **
    +static inline struct perf_event * __percpu *
    register_wide_hw_breakpoint(struct perf_event_attr *attr,
    perf_overflow_handler_t triggered) { return NULL; }
    static inline int
    @@ -109,7 +109,7 @@ static inline int
    __register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
    static inline void unregister_hw_breakpoint(struct perf_event *bp) { }
    static inline void
    -unregister_wide_hw_breakpoint(struct perf_event **cpu_events) { }
    +unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events) { }
    static inline int
    reserve_bp_slot(struct perf_event *bp) {return -ENOSYS; }
    static inline void release_bp_slot(struct perf_event *bp) { }
    diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
    index 967e661..6542eac 100644
    --- a/kernel/hw_breakpoint.c
    +++ b/kernel/hw_breakpoint.c
    @@ -413,17 +413,17 @@ EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
    *
    * @return a set of per_cpu pointers to perf events
    */
    -struct perf_event **
    +struct perf_event * __percpu *
    register_wide_hw_breakpoint(struct perf_event_attr *attr,
    perf_overflow_handler_t triggered)
    {
    - struct perf_event **cpu_events, **pevent, *bp;
    + struct perf_event * __percpu *cpu_events, **pevent, *bp;
    long err;
    int cpu;

    cpu_events = alloc_percpu(typeof(*cpu_events));
    if (!cpu_events)
    - return ERR_PTR(-ENOMEM);
    + return (void __percpu __force *)ERR_PTR(-ENOMEM);

    get_online_cpus();
    for_each_online_cpu(cpu) {
    @@ -451,7 +451,7 @@ fail:
    put_online_cpus();

    free_percpu(cpu_events);
    - return ERR_PTR(err);
    + return (void __percpu __force *)ERR_PTR(err);
    }
    EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);

    @@ -459,7 +459,7 @@ EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);
    * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel
    * @cpu_events: the per cpu set of events to unregister
    */
    -void unregister_wide_hw_breakpoint(struct perf_event **cpu_events)
    +void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events)
    {
    int cpu;
    struct perf_event **pevent;
    diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c
    index c69cbe9..bd0f337 100644
    --- a/samples/hw_breakpoint/data_breakpoint.c
    +++ b/samples/hw_breakpoint/data_breakpoint.c
    @@ -34,7 +34,7 @@
    #include <linux/perf_event.h>
    #include <linux/hw_breakpoint.h>

    -struct perf_event **sample_hbp;
    +struct perf_event * __percpu *sample_hbp;

    static char ksym_name[KSYM_NAME_LEN] = "pid_max";
    module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO);
    @@ -61,8 +61,8 @@ static int __init hw_break_module_init(void)
    attr.bp_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;

    sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler);
    - if (IS_ERR(sample_hbp)) {
    - ret = PTR_ERR(sample_hbp);
    + if (IS_ERR((void __force *)sample_hbp)) {
    + ret = PTR_ERR((void __force *)sample_hbp);
    goto fail;
    }


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