On Mon, Jul 14, 2014 at 07:30:43PM +0200, Jens Axboe wrote:
> Why not just makes this:
> 
>       local_irq_save(flags);
>       kcpu = this_put_ptr(...);
>       ...
> 
> and get rid of the preemption bits, it's a bit redundant now you need to 
> kill local interrupts anyway.

*nod*.  I'll add the following cleanup patch, as the first version already 
got merged into another tree.

                -ben

diff --git a/fs/aio.c b/fs/aio.c
index 1c9c5f0..104da62 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -832,10 +832,8 @@ static void put_reqs_available(struct kioctx *ctx, 
unsigned nr)
        struct kioctx_cpu *kcpu;
        unsigned long flags;
 
-       preempt_disable();
-       kcpu = this_cpu_ptr(ctx->cpu);
-
        local_irq_save(flags);
+       kcpu = this_cpu_ptr(ctx->cpu);
        kcpu->reqs_available += nr;
 
        while (kcpu->reqs_available >= ctx->req_batch * 2) {
@@ -844,7 +842,6 @@ static void put_reqs_available(struct kioctx *ctx, unsigned 
nr)
        }
 
        local_irq_restore(flags);
-       preempt_enable();
 }
 
 static bool get_reqs_available(struct kioctx *ctx)
@@ -853,10 +850,8 @@ static bool get_reqs_available(struct kioctx *ctx)
        bool ret = false;
        unsigned long flags;
 
-       preempt_disable();
-       kcpu = this_cpu_ptr(ctx->cpu);
-
        local_irq_save(flags);
+       kcpu = this_cpu_ptr(ctx->cpu);
        if (!kcpu->reqs_available) {
                int old, avail = atomic_read(&ctx->reqs_available);
 
@@ -876,7 +871,6 @@ static bool get_reqs_available(struct kioctx *ctx)
        kcpu->reqs_available--;
 out:
        local_irq_restore(flags);
-       preempt_enable();
        return ret;
 }
 

                -ben
-- 
"Thought is the essence of where you are now."
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