lkml.org 
[lkml]   [2011]   [May]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 2/4] comm: Add lock-free task->comm accessor
    Date
    This patch adds __get_task_comm() which returns the task->comm value
    without taking the comm_lock. This function may return null or
    incomplete comm values, and is only present for performance critical
    paths that can handle these pitfalls.

    CC: Joe Perches <joe@perches.com>
    CC: Ingo Molnar <mingo@elte.hu>
    CC: Michal Nazarewicz <mina86@mina86.com>
    CC: Andy Whitcroft <apw@canonical.com>
    CC: Jiri Slaby <jirislaby@gmail.com>
    CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    CC: David Rientjes <rientjes@google.com>
    CC: Dave Hansen <dave@linux.vnet.ibm.com>
    CC: Andrew Morton <akpm@linux-foundation.org>
    CC: linux-mm@kvack.org
    Signed-off-by: John Stultz <john.stultz@linaro.org>
    ---
    fs/exec.c | 13 +++++++++++++
    include/linux/sched.h | 1 +
    2 files changed, 14 insertions(+), 0 deletions(-)

    diff --git a/fs/exec.c b/fs/exec.c
    index 34fa611..7e79c97 100644
    --- a/fs/exec.c
    +++ b/fs/exec.c
    @@ -996,6 +996,19 @@ static void flush_old_files(struct files_struct * files)
    spin_unlock(&files->file_lock);
    }

    +/**
    + * __get_task_comm - Unlocked accessor to task comm value
    + *
    + * This function returns the task->comm value without
    + * taking the comm_lock. This method is only for performance
    + * critical paths, and may return a null or incomplete comm
    + * value.
    + */
    +char *__get_task_comm(struct task_struct *tsk)
    +{
    + return tsk->comm;
    +}
    +
    char *get_task_comm(char *buf, struct task_struct *tsk)
    {
    unsigned long flags;
    diff --git a/include/linux/sched.h b/include/linux/sched.h
    index f8a7cdf..5e3c25a 100644
    --- a/include/linux/sched.h
    +++ b/include/linux/sched.h
    @@ -2189,6 +2189,7 @@ struct task_struct *fork_idle(int);

    extern void set_task_comm(struct task_struct *tsk, char *from);
    extern char *get_task_comm(char *to, struct task_struct *tsk);
    +extern char *__get_task_comm(struct task_struct *tsk);

    #ifdef CONFIG_SMP
    extern unsigned long wait_task_inactive(struct task_struct *, long match_state);
    --
    1.7.3.2.146.gca209


    \
     
     \ /
      Last update: 2011-05-18 03:43    [W:0.044 / U:0.052 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site