Re: [PATCH v4] perf_counter: Fix race in attaching counters totasks and exiting
From: Paul Mackerras
Date: Thu May 28 2009 - 08:18:34 EST
Peter Zijlstra writes:
> The poor task will now have to wait for yet another RCU grace period,
> but yeah :-)
I moved the put_task_struct into put_ctx, inside the if, so the poor
task won't get impatient. :)
> Looks good, although lockdep will complain, the proper annotation would
> be spin_lock_nested_lock(&ctx->lock, &rq->lock), but since we don't have
> access to the rq here, we should change the second spin_lock, to:
> spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
Ah OK, thanks.
> You jump into an rcu_read_lock() section there.
Oops. I'll fix that. I also need to use spin_[un]lock_irq in there.
New version coming. Thanks for the review.
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