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target: Drop lun_sep_lock for se_lun->lun_se_dev RCU usage

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With se_port and t10_alua_tg_pt_gp_member being absored into se_lun,
there is no need for an extra lock to protect se_lun->lun_se_dev
assignment.

This patch also converts backend drivers to use call_rcu() release
to allow any se_device readers to complete.  The call_rcu() instead
of kfree_rcu() is required here because se_device is embedded into
the backend driver specific structure.

Also, convert se_lun->lun_stats to use atomic_long_t within the
target_complete_ok_work() completion callback, and add FIXME for
transport_lookup_tmr_lun() with se_lun->lun_ref.

Finally, update sbp_update_unit_directory() special case usage with
proper rcu_dereference_raw() and configfs symlink comment.

Reported-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Chris Boot <bootc@bootc.net>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Nicholas Bellinger
2015-05-19 00:03:07 -07:00
parent adf653f92f
commit 4cc987eaff
13 changed files with 175 additions and 115 deletions
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10
include/target/target_core_base.h
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@@ -690,9 +690,9 @@ struct se_port_stat_grps {
};
struct scsi_port_stats {
u32 cmd_pdus;
u64 tx_data_octets;
u64 rx_data_octets;
atomic_long_t cmd_pdus;
atomic_long_t tx_data_octets;
atomic_long_t rx_data_octets;
};
struct se_lun {
@@ -705,7 +705,6 @@ struct se_lun {
u32 unpacked_lun;
u32 lun_index;
atomic_t lun_acl_count;
spinlock_t lun_sep_lock;
struct se_device __rcu *lun_se_dev;
struct list_head lun_deve_list;
@@ -818,6 +817,9 @@ struct se_device {
struct se_lun xcopy_lun;
/* Protection Information */
int prot_length;
/* For se_lun->lun_se_dev RCU read-side critical access */
u32 hba_index;
struct rcu_head rcu_head;
};
struct se_hba {