[PATCH] exit_io_context: don't disable irqs

We don't need to disable irqs to clear current->io_context, it is protected
by ->alloc_lock. Even IF it was possible to submit I/O from IRQ on behalf of
current this irq_disable() can't help: current_io_context() will re-instantiate
->io_context after irq_enable().

We don't need task_lock() or local_irq_disable() to clear ioc->task. This can't
prevent other CPUs from playing with our io_context anyway.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 2 insertions, 5 deletions

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 57992ae511c2..f757ed413214 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -3629,25 +3629,22 @@ EXPORT_SYMBOL(put_io_context);
 /* Called by the exitting task */
 void exit_io_context(void)
 {
-        unsigned long flags;
         struct io_context *ioc;
         struct cfq_io_context *cic;
 
-        local_irq_save(flags);
         task_lock(current);
         ioc = current->io_context;
         current->io_context = NULL;
-        ioc->task = NULL;
         task_unlock(current);
-        local_irq_restore(flags);
 
+        ioc->task = NULL;
         if (ioc->aic && ioc->aic->exit)
                 ioc->aic->exit(ioc->aic);
         if (ioc->cic_root.rb_node != NULL) {
                 cic = rb_entry(rb_first(&ioc->cic_root), struct cfq_io_context, rb_node);
                 cic->exit(ioc);
         }
- 
+
         put_io_context(ioc);
 }