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Commit 555b270e authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

iscsi-target: Fix connection reset hang with percpu_ida_alloc 



This patch addresses a bug where connection reset would hang
indefinately once percpu_ida_alloc() was starved for tags, due
to the fact that it always assumed uninterruptible sleep mode.

So now make percpu_ida_alloc() check for signal_pending_state() for
making interruptible sleep optional, and convert iscsit_allocate_cmd()
to set TASK_INTERRUPTIBLE for GFP_KERNEL, or TASK_RUNNING for
GFP_ATOMIC.

Reported-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: <stable@vger.kernel.org> #3.12+
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 6f6b5d1e

drivers/target/iscsi/iscsi_target_util.c

+1 −1
Original line number Diff line number Diff line
@@ -156,7 +156,7 @@ struct iscsi_cmd *iscsit_allocate_cmd(struct iscsi_conn *conn, gfp_t gfp_mask) 
{

	struct iscsi_cmd *cmd;

	struct se_session *se_sess = conn->sess->se_sess;

	int size, tag, state = (gfp_mask & __GFP_WAIT) ? TASK_UNINTERRUPTIBLE :

	int size, tag, state = (gfp_mask & __GFP_WAIT) ? TASK_INTERRUPTIBLE :

				TASK_RUNNING;



	tag = percpu_ida_alloc(&se_sess->sess_tag_pool, state);

lib/percpu_ida.c

+7 −2
Original line number Diff line number Diff line
@@ -138,14 +138,14 @@ static inline unsigned alloc_local_tag(struct percpu_ida_cpu *tags) 
 * tag_pool_init()), or otherwise -ENOSPC on allocation failure.

 *

 * Safe to be called from interrupt context (assuming it isn't passed

 * TASK_UNINTERRUPTIBLE, of course).

 * TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, of course).

 *

 * @gfp indicates whether or not to wait until a free id is available (it's not

 * used for internal memory allocations); thus if passed __GFP_WAIT we may sleep

 * however long it takes until another thread frees an id (same semantics as a

 * mempool).

 *

 * Will not fail if passed TASK_UNINTERRUPTIBLE.

 * Will not fail if passed TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE.

 */

int percpu_ida_alloc(struct percpu_ida *pool, int state)

{
@@ -195,6 +195,11 @@ int percpu_ida_alloc(struct percpu_ida *pool, int state) 
		if (tag >= 0 || state == TASK_RUNNING)

			break;



		if (signal_pending_state(state, current)) {

			tag = -ERESTARTSYS;

			break;

		}



		schedule();



		local_irq_save(flags);