Hi Greg,

On Mon, 2014-02-10 at 09:39 -0800, [email protected] wrote:
> This is a note to let you know that I've just added the patch titled
> 
>     percpu_ida: Make percpu_ida_alloc + callers accept task state bitmask
> 
> to the 3.13-stable tree which can be found at:
>     
> http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> 
> The filename of the patch is:
>      percpu_ida-make-percpu_ida_alloc-callers-accept-task-state-bitmask.patch
> and it can be found in the queue-3.13 subdirectory.
> 
> If you, or anyone else, feels it should not be added to the stable tree,
> please let <[email protected]> know about it.
> 
> 

So this patch is intended to go along with:
[for-v3.13.y 2/2] iscsi-target: Fix connection reset hang with percpu_ida_alloc
http://www.spinics.net/lists/target-devel/msg06192.html

Please include commit 555b270e25b0279b98083518a85f4b1da144a181 for both
v3.1[3,2].y code along with this particular percpu_ida patch.

Thanks,

--nab

> From 6f6b5d1ec56acdeab0503d2b823f6f88a0af493e Mon Sep 17 00:00:00 2001
> From: Kent Overstreet <[email protected]>
> Date: Sun, 19 Jan 2014 08:26:37 +0000
> Subject: percpu_ida: Make percpu_ida_alloc + callers accept task state bitmask
> 
> From: Kent Overstreet <[email protected]>
> 
> commit 6f6b5d1ec56acdeab0503d2b823f6f88a0af493e upstream.
> 
> 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 <[email protected]>
> Cc: Linus Torvalds <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Jens Axboe <[email protected]>
> Signed-off-by: Kent Overstreet <[email protected]>
> Signed-off-by: Nicholas Bellinger <[email protected]>
> Signed-off-by: Greg Kroah-Hartman <[email protected]>
> 
> ---
>  block/blk-mq-tag.c                       |    6 ++++--
>  drivers/target/iscsi/iscsi_target_util.c |    8 ++++++--
>  drivers/target/tcm_fc/tfc_cmd.c          |    2 +-
>  drivers/vhost/scsi.c                     |    2 +-
>  include/linux/percpu_ida.h               |    3 ++-
>  lib/percpu_ida.c                         |   16 +++++++++-------
>  6 files changed, 23 insertions(+), 14 deletions(-)
> 
> --- a/block/blk-mq-tag.c
> +++ b/block/blk-mq-tag.c
> @@ -36,7 +36,8 @@ static unsigned int __blk_mq_get_tag(str
>  {
>       int tag;
>  
> -     tag = percpu_ida_alloc(&tags->free_tags, gfp);
> +     tag = percpu_ida_alloc(&tags->free_tags, (gfp & __GFP_WAIT) ?
> +                            TASK_UNINTERRUPTIBLE : TASK_RUNNING);
>       if (tag < 0)
>               return BLK_MQ_TAG_FAIL;
>       return tag + tags->nr_reserved_tags;
> @@ -52,7 +53,8 @@ static unsigned int __blk_mq_get_reserve
>               return BLK_MQ_TAG_FAIL;
>       }
>  
> -     tag = percpu_ida_alloc(&tags->reserved_tags, gfp);
> +     tag = percpu_ida_alloc(&tags->reserved_tags, (gfp & __GFP_WAIT) ?
> +                            TASK_UNINTERRUPTIBLE : TASK_RUNNING);
>       if (tag < 0)
>               return BLK_MQ_TAG_FAIL;
>       return tag;
> --- a/drivers/target/iscsi/iscsi_target_util.c
> +++ b/drivers/target/iscsi/iscsi_target_util.c
> @@ -156,9 +156,13 @@ struct iscsi_cmd *iscsit_allocate_cmd(st
>  {
>       struct iscsi_cmd *cmd;
>       struct se_session *se_sess = conn->sess->se_sess;
> -     int size, tag;
> +     int size, tag, state = (gfp_mask & __GFP_WAIT) ? TASK_UNINTERRUPTIBLE :
> +                             TASK_RUNNING;
> +
> +     tag = percpu_ida_alloc(&se_sess->sess_tag_pool, state);
> +     if (tag < 0)
> +             return NULL;
>  
> -     tag = percpu_ida_alloc(&se_sess->sess_tag_pool, gfp_mask);
>       size = sizeof(struct iscsi_cmd) + conn->conn_transport->priv_size;
>       cmd = (struct iscsi_cmd *)(se_sess->sess_cmd_map + (tag * size));
>       memset(cmd, 0, size);
> --- a/drivers/target/tcm_fc/tfc_cmd.c
> +++ b/drivers/target/tcm_fc/tfc_cmd.c
> @@ -438,7 +438,7 @@ static void ft_recv_cmd(struct ft_sess *
>       struct se_session *se_sess = sess->se_sess;
>       int tag;
>  
> -     tag = percpu_ida_alloc(&se_sess->sess_tag_pool, GFP_ATOMIC);
> +     tag = percpu_ida_alloc(&se_sess->sess_tag_pool, TASK_RUNNING);
>       if (tag < 0)
>               goto busy;
>  
> --- a/drivers/vhost/scsi.c
> +++ b/drivers/vhost/scsi.c
> @@ -728,7 +728,7 @@ vhost_scsi_get_tag(struct vhost_virtqueu
>       }
>       se_sess = tv_nexus->tvn_se_sess;
>  
> -     tag = percpu_ida_alloc(&se_sess->sess_tag_pool, GFP_ATOMIC);
> +     tag = percpu_ida_alloc(&se_sess->sess_tag_pool, TASK_RUNNING);
>       if (tag < 0) {
>               pr_err("Unable to obtain tag for tcm_vhost_cmd\n");
>               return ERR_PTR(-ENOMEM);
> --- a/include/linux/percpu_ida.h
> +++ b/include/linux/percpu_ida.h
> @@ -4,6 +4,7 @@
>  #include <linux/types.h>
>  #include <linux/bitops.h>
>  #include <linux/init.h>
> +#include <linux/sched.h>
>  #include <linux/spinlock_types.h>
>  #include <linux/wait.h>
>  #include <linux/cpumask.h>
> @@ -61,7 +62,7 @@ struct percpu_ida {
>  /* Max size of percpu freelist, */
>  #define IDA_DEFAULT_PCPU_SIZE        ((IDA_DEFAULT_PCPU_BATCH_MOVE * 3) / 2)
>  
> -int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp);
> +int percpu_ida_alloc(struct percpu_ida *pool, int state);
>  void percpu_ida_free(struct percpu_ida *pool, unsigned tag);
>  
>  void percpu_ida_destroy(struct percpu_ida *pool);
> --- a/lib/percpu_ida.c
> +++ b/lib/percpu_ida.c
> @@ -132,22 +132,22 @@ static inline unsigned alloc_local_tag(s
>  /**
>   * 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 *
>                *
>                * 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 *
>               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 *
>               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);
> 
> 
> Patches currently in stable-queue which might be from [email protected] are
> 
> queue-3.13/percpu_ida-make-percpu_ida_alloc-callers-accept-task-state-bitmask.patch


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