the pfm_fasync() function must not lock the context and mask interrupts
because the fasync_helper() function may allocate memory and this could
lead to sleeping, due to SLAB_KERNEL memory type, if no memory is available.
Going to sleep with interrupts mask is not allowed otherwise you have a deadlock.
The locking of the context is not necessary in this function because it is protected
by caller via get_fd()/put_fd(). The async_queue is also protected. Serialization to
pfm_fasync() is also ensured by caller. The fix is to drop the PROTECT_CTX()
and UNPROTECT_CTX() calls.
signed-off-by: stephane eranian <eranian@hpl.hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>