From 6f6b5d1ec56acdeab0503d2b823f6f88a0af493e Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Sun, 19 Jan 2014 08:26:37 +0000 Subject: percpu_ida: Make percpu_ida_alloc + callers accept task state bitmask This patch changes percpu_ida_alloc() + callers to accept task state bitmask for prepare_to_wait() for code like target/iscsi that needs it for interruptible sleep, that is provided in a subsequent patch. It now expects TASK_UNINTERRUPTIBLE when the caller is able to sleep waiting for a new tag, or TASK_RUNNING when the caller cannot sleep, and is forced to return a negative value when no tags are available. v2 changes: - Include blk-mq + tcm_fc + vhost/scsi + target/iscsi changes - Drop signal_pending_state() call v3 changes: - Only call prepare_to_wait() + finish_wait() when != TASK_RUNNING (PeterZ) Reported-by: Linus Torvalds Cc: Linus Torvalds Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Jens Axboe Signed-off-by: Kent Overstreet Cc: #3.12+ Signed-off-by: Nicholas Bellinger --- lib/percpu_ida.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) (limited to 'lib') diff --git a/lib/percpu_ida.c b/lib/percpu_ida.c index 9d054bf91d0f..58b671484ac2 100644 --- a/lib/percpu_ida.c +++ b/lib/percpu_ida.c @@ -132,22 +132,22 @@ static inline unsigned alloc_local_tag(struct percpu_ida_cpu *tags) /** * percpu_ida_alloc - allocate a tag * @pool: pool to allocate from - * @gfp: gfp flags + * @state: task state for prepare_to_wait * * Returns a tag - an integer in the range [0..nr_tags) (passed to * tag_pool_init()), or otherwise -ENOSPC on allocation failure. * * Safe to be called from interrupt context (assuming it isn't passed - * __GFP_WAIT, of course). + * TASK_UNINTERRUPTIBLE, 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 __GFP_WAIT. + * Will not fail if passed TASK_UNINTERRUPTIBLE. */ -int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp) +int percpu_ida_alloc(struct percpu_ida *pool, int state) { DEFINE_WAIT(wait); struct percpu_ida_cpu *tags; @@ -174,7 +174,8 @@ int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp) * * global lock held and irqs disabled, don't need percpu lock */ - prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE); + if (state != TASK_RUNNING) + prepare_to_wait(&pool->wait, &wait, state); if (!tags->nr_free) alloc_global_tags(pool, tags); @@ -191,7 +192,7 @@ int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp) spin_unlock(&pool->lock); local_irq_restore(flags); - if (tag >= 0 || !(gfp & __GFP_WAIT)) + if (tag >= 0 || state == TASK_RUNNING) break; schedule(); @@ -199,8 +200,9 @@ int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp) local_irq_save(flags); tags = this_cpu_ptr(pool->tag_cpu); } + if (state != TASK_RUNNING) + finish_wait(&pool->wait, &wait); - finish_wait(&pool->wait, &wait); return tag; } EXPORT_SYMBOL_GPL(percpu_ida_alloc); -- cgit v1.2.3-70-g09d2 From 555b270e25b0279b98083518a85f4b1da144a181 Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Mon, 20 Jan 2014 03:36:24 +0000 Subject: 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: Linus Torvalds Cc: Kent Overstreet Cc: #3.12+ Signed-off-by: Nicholas Bellinger --- drivers/target/iscsi/iscsi_target_util.c | 2 +- lib/percpu_ida.c | 9 +++++++-- 2 files changed, 8 insertions(+), 3 deletions(-) (limited to 'lib') diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c index 9b8e1db1257b..5477ecabc00e 100644 --- a/drivers/target/iscsi/iscsi_target_util.c +++ b/drivers/target/iscsi/iscsi_target_util.c @@ -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); diff --git a/lib/percpu_ida.c b/lib/percpu_ida.c index 58b671484ac2..7be235f1a70b 100644 --- a/lib/percpu_ida.c +++ b/lib/percpu_ida.c @@ -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); -- cgit v1.2.3-70-g09d2