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Commit 6fddcb77 authored by Mike Christie's avatar Mike Christie Committed by Nicholas Bellinger
Browse files

tcmu: remove commands_lock 



No need for the commands_lock. The cmdr_lock is already held during
idr addition and deletion, so just grab it during traversal.

Note: This also fixes a issue where we should have been using at
least _bh locking in tcmu_handle_completions when taking the commands
lock to prevent the case where tcmu_handle_completions could be
interrupted by a timer softirq while the commands_lock is held.

Signed-off-by: default avatarMike Christie <mchristi@redhat.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 488ebe4c

drivers/target/target_core_user.c

+3 −10
Original line number Diff line number Diff line
@@ -139,7 +139,6 @@ struct tcmu_dev { 
	struct radix_tree_root data_blocks;



	struct idr commands;

	spinlock_t commands_lock;



	struct timer_list timeout;

	unsigned int cmd_time_out;
@@ -1014,10 +1013,7 @@ static unsigned int tcmu_handle_completions(struct tcmu_dev *udev) 
		}

		WARN_ON(tcmu_hdr_get_op(entry->hdr.len_op) != TCMU_OP_CMD);



		spin_lock(&udev->commands_lock);

		cmd = idr_remove(&udev->commands, entry->hdr.cmd_id);

		spin_unlock(&udev->commands_lock);



		if (!cmd) {

			pr_err("cmd_id not found, ring is broken\n");

			set_bit(TCMU_DEV_BIT_BROKEN, &udev->flags);
@@ -1115,7 +1111,6 @@ static struct se_device *tcmu_alloc_device(struct se_hba *hba, const char *name) 


	INIT_LIST_HEAD(&udev->timedout_entry);

	idr_init(&udev->commands);

	spin_lock_init(&udev->commands_lock);



	timer_setup(&udev->timeout, tcmu_device_timedout, 0);
@@ -1333,16 +1328,14 @@ static void tcmu_dev_kref_release(struct kref *kref) 
	spin_unlock_bh(&timed_out_udevs_lock);



	/* Upper layer should drain all requests before calling this */

	spin_lock_irq(&udev->commands_lock);

	mutex_lock(&udev->cmdr_lock);

	idr_for_each_entry(&udev->commands, cmd, i) {

		if (tcmu_check_and_free_pending_cmd(cmd) != 0)

			all_expired = false;

	}

	idr_destroy(&udev->commands);

	spin_unlock_irq(&udev->commands_lock);

	WARN_ON(!all_expired);



	mutex_lock(&udev->cmdr_lock);

	tcmu_blocks_release(&udev->data_blocks, 0, udev->dbi_max + 1);

	mutex_unlock(&udev->cmdr_lock);
@@ -2060,9 +2053,9 @@ static void check_timedout_devices(void) 
		list_del_init(&udev->timedout_entry);

		spin_unlock_bh(&timed_out_udevs_lock);



		spin_lock(&udev->commands_lock);

		mutex_lock(&udev->cmdr_lock);

		idr_for_each(&udev->commands, tcmu_check_expired_cmd, NULL);

		spin_unlock(&udev->commands_lock);

		mutex_unlock(&udev->cmdr_lock);



		spin_lock_bh(&timed_out_udevs_lock);

	}