lkml.org 
[lkml]   [2009]   [May]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH RFC] perf_counter: Don't swap contexts containing locked mutex
From
Date
On Fri, 2009-05-29 at 10:06 +0200, Peter Zijlstra wrote:

> static struct perf_counter_ctx *pin_ctx(struct perf_counter *counter, u64 *old_gen)
> {
> struct perf_counter_context *ctx;
> unsigned long flags;
>
> rcu_read_lock();
> retry:
> ctx = rcu_dereference(counter->ctx);
> spin_lock_irqsave(&ctx->lock, flags);
> if (ctx != rcu_dereference(counter->ctx))
> goto retry;
>
> *old_gen = ctx->generation;
> ctx->generation = ~0ULL;
> spin_unlock_irqrestore(&ctx->lock, flags);
> rcu_read_unlock();
>
> return ctx;
> }
>
> static void unpin_ctx(struct perf_counter_ctx *ctx, u64 old_gen)
> {
> unsigned long flags;
>
> spin_lock_irqsave(&ctx->lock, flags);
> ctx->generation = old_gen;
> spin_unlock_irqrestore(&ctx->lock, flags);
> }

OK, I think I got this wrong, counter->ctx isn't the problem.
task->perf_counter_ctx is.

Still would be nice to write it in the above form. I'll go over the code
again to see who else might want it.


\
 
 \ /
  Last update: 2009-05-29 10:15    [W:0.050 / U:0.228 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site