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    Subject[PATCH 1/6] Free up pf flag PF_KSOFTIRQD -v1
    Date
    Cleanup patch, freeing up PF_KSOFTIRQD and use per_cpu ksoftirqd pointer
    instead, as suggested by Eric Dumazet.

    Tested-by: Shaun Ruffell <sruffell@digium.com>

    Signed-off-by: Venkatesh Pallipadi <venki@google.com>
    ---
    include/linux/interrupt.h | 7 +++++++
    include/linux/sched.h | 1 -
    kernel/sched.c | 2 +-
    kernel/softirq.c | 3 +--
    4 files changed, 9 insertions(+), 4 deletions(-)

    diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
    index 01b2816..0473d88 100644
    --- a/include/linux/interrupt.h
    +++ b/include/linux/interrupt.h
    @@ -426,6 +426,13 @@ extern void raise_softirq(unsigned int nr);
    */
    DECLARE_PER_CPU(struct list_head [NR_SOFTIRQS], softirq_work_list);

    +DECLARE_PER_CPU(struct task_struct *, ksoftirqd);
    +
    +static inline struct task_struct *this_cpu_ksoftirqd(void)
    +{
    + return this_cpu_read(ksoftirqd);
    +}
    +
    /* Try to send a softirq to a remote cpu. If this cannot be done, the
    * work will be queued to the local cpu.
    */
    diff --git a/include/linux/sched.h b/include/linux/sched.h
    index 0383601..0b25c60 100644
    --- a/include/linux/sched.h
    +++ b/include/linux/sched.h
    @@ -1691,7 +1691,6 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
    /*
    * Per process flags
    */
    -#define PF_KSOFTIRQD 0x00000001 /* I am ksoftirqd */
    #define PF_STARTING 0x00000002 /* being created */
    #define PF_EXITING 0x00000004 /* getting shut down */
    #define PF_EXITPIDONE 0x00000008 /* pi exit done on shut down */
    diff --git a/kernel/sched.c b/kernel/sched.c
    index abf8440..fae668b 100644
    --- a/kernel/sched.c
    +++ b/kernel/sched.c
    @@ -1986,7 +1986,7 @@ void account_system_vtime(struct task_struct *curr)
    */
    if (hardirq_count())
    per_cpu(cpu_hardirq_time, cpu) += delta;
    - else if (in_serving_softirq() && !(curr->flags & PF_KSOFTIRQD))
    + else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
    per_cpu(cpu_softirq_time, cpu) += delta;

    local_irq_restore(flags);
    diff --git a/kernel/softirq.c b/kernel/softirq.c
    index f02a9df..f7a88af 100644
    --- a/kernel/softirq.c
    +++ b/kernel/softirq.c
    @@ -54,7 +54,7 @@ EXPORT_SYMBOL(irq_stat);

    static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp;

    -static DEFINE_PER_CPU(struct task_struct *, ksoftirqd);
    +DEFINE_PER_CPU(struct task_struct *, ksoftirqd);

    char *softirq_to_name[NR_SOFTIRQS] = {
    "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL",
    @@ -719,7 +719,6 @@ static int run_ksoftirqd(void * __bind_cpu)
    {
    set_current_state(TASK_INTERRUPTIBLE);

    - current->flags |= PF_KSOFTIRQD;
    while (!kthread_should_stop()) {
    preempt_disable();
    if (!local_softirq_pending()) {
    --
    1.7.1


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