| Message ID | 20170208222507.25715-18-bart.vanassche@sandisk.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On 02/08/2017 11:24 PM, Bart Van Assche wrote: > This reference count keeps track of the number of references held > by a target driver on a command. se_cmd.complete is set once the > target driver has released all references it held on a command. > > Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> > Cc: Hannes Reinecke <hare@suse.com> > Cc: Christoph Hellwig <hch@lst.de> > Cc: Andy Grover <agrover@redhat.com> > Cc: David Disseldorp <ddiss@suse.de> > --- > drivers/target/target_core_internal.h | 1 + > drivers/target/target_core_tmr.c | 8 ++++---- > drivers/target/target_core_transport.c | 24 +++++++++++++++++++++--- > include/target/target_core_base.h | 2 ++ > 4 files changed, 28 insertions(+), 7 deletions(-) > > diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h > index 9ab7090f7c83..48de996ad28d 100644 > --- a/drivers/target/target_core_internal.h > +++ b/drivers/target/target_core_internal.h > @@ -146,6 +146,7 @@ int transport_dump_vpd_assoc(struct t10_vpd *, unsigned char *, int); > int transport_dump_vpd_ident_type(struct t10_vpd *, unsigned char *, int); > int transport_dump_vpd_ident(struct t10_vpd *, unsigned char *, int); > void transport_clear_lun_ref(struct se_lun *); > +int __target_put_sess_cmd(struct se_cmd *se_cmd); > void transport_send_task_abort(struct se_cmd *); > sense_reason_t target_cmd_size_check(struct se_cmd *cmd, unsigned int size); > void target_qf_do_work(struct work_struct *work); > diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c > index 367799b4dde1..161c8b8482db 100644 > --- a/drivers/target/target_core_tmr.c > +++ b/drivers/target/target_core_tmr.c > @@ -188,7 +188,7 @@ void core_tmr_abort_task( > if (!tmr->tmr_dev && > transport_lookup_tmr_lun(tmr->task_cmd, > se_cmd->orig_fe_lun) < 0) { > - target_put_sess_cmd(se_cmd); > + __target_put_sess_cmd(se_cmd); > continue; > } > > @@ -199,7 +199,7 @@ void core_tmr_abort_task( > transport_wait_for_tasks(se_cmd); > > transport_cmd_finish_abort(se_cmd, true); > - target_put_sess_cmd(se_cmd); > + __target_put_sess_cmd(se_cmd); > > printk("ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for" > " ref_tag: %llu\n", ref_tag); > @@ -299,7 +299,7 @@ static void core_tmr_drain_tmr_list( > transport_wait_for_tasks(cmd); > > transport_cmd_finish_abort(cmd, 1); > - target_put_sess_cmd(cmd); > + __target_put_sess_cmd(cmd); > } > } > > @@ -398,7 +398,7 @@ static void core_tmr_drain_state_list( > transport_wait_for_tasks(cmd); > > core_tmr_handle_tas_abort(cmd, tas); > - target_put_sess_cmd(cmd); > + __target_put_sess_cmd(cmd); > } > } > > diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c > index 8f2169e92771..533b584c2806 100644 > --- a/drivers/target/target_core_transport.c > +++ b/drivers/target/target_core_transport.c > @@ -1217,6 +1217,7 @@ void transport_init_se_cmd( > init_completion(&cmd->cmd_wait_comp); > spin_lock_init(&cmd->t_state_lock); > kref_init(&cmd->cmd_kref); > + atomic_set(&cmd->tgt_ref, 1); > cmd->transport_state = CMD_T_DEV_ACTIVE; > > cmd->se_tfo = tfo; > @@ -2554,6 +2555,7 @@ int target_get_sess_cmd(struct se_cmd *se_cmd, bool ack_kref) > if (!kref_get_unless_zero(&se_cmd->cmd_kref)) > return -EINVAL; > > + atomic_inc(&se_cmd->tgt_ref); > se_cmd->se_cmd_flags |= SCF_ACK_KREF; > } > > @@ -2590,6 +2592,8 @@ static void target_release_cmd_kref(struct kref *kref) > unsigned long flags; > bool fabric_stop; > > + WARN_ON_ONCE(atomic_read(&se_cmd->tgt_ref) != 0); > + > if (se_sess) { > spin_lock_irqsave(&se_sess->sess_cmd_lock, flags); > > @@ -2614,15 +2618,29 @@ static void target_release_cmd_kref(struct kref *kref) > } > > /** > + * __target_put_sess_cmd - drop a reference obtained by kref_get_unless_zero() > + */ > +int __target_put_sess_cmd(struct se_cmd *se_cmd) > +{ > + return kref_put(&se_cmd->cmd_kref, target_release_cmd_kref); > +} > + > +/** > * target_put_sess_cmd - decrease the command reference count > - * @se_cmd: command to drop a reference from > + * @se_cmd: Drop a reference obtained by target_get_sess_cmd(). > * > * Returns 1 if and only if this target_put_sess_cmd() call caused the > * refcount to drop to zero. Returns zero otherwise. > */ > int target_put_sess_cmd(struct se_cmd *se_cmd) > { > - return kref_put(&se_cmd->cmd_kref, target_release_cmd_kref); > + long ref = atomic_dec_return(&se_cmd->tgt_ref); > + > + WARN_ON_ONCE(ref < 0); > + if (ref == 0) > + complete(&se_cmd->complete); > + > + return __target_put_sess_cmd(se_cmd); > } > EXPORT_SYMBOL(target_put_sess_cmd); > > @@ -2680,7 +2698,7 @@ void target_wait_for_sess_cmds(struct se_session *se_sess) > tas = (se_cmd->transport_state & CMD_T_TAS); > spin_unlock_irqrestore(&se_cmd->t_state_lock, flags); > > - if (!target_put_sess_cmd(se_cmd)) { > + if (!__target_put_sess_cmd(se_cmd)) { > if (tas) > target_put_sess_cmd(se_cmd); > } > diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h > index fb87f0e5d0d6..c84e5eecb94d 100644 > --- a/include/target/target_core_base.h > +++ b/include/target/target_core_base.h > @@ -495,7 +495,9 @@ struct se_cmd { > #define CMD_T_FABRIC_STOP (1 << 11) > spinlock_t t_state_lock; > struct kref cmd_kref; > + atomic_t tgt_ref; > struct completion t_transport_stop_comp; > + struct completion complete; > > struct work_struct work; > > What a curious construct. Why not a normal kref here? Using an atomic here would make sense if you need to bail out if both counters would be independent. But as it stands the 'tgt_kref' _has_ to be '0' before the final call to __target_put_sess_cmd() (otherwise you'll end up with a hanging wait_for_completion). Which means that the lifetime of 'tgt_kref' is bounded by the lifetime of se_cmd, and we can just add a second kref there. Cheers, Hannes
On Wed, 2017-02-08 at 14:24 -0800, Bart Van Assche wrote: > This reference count keeps track of the number of references held > by a target driver on a command. se_cmd.complete is set once the > target driver has released all references it held on a command. > > Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> > Cc: Hannes Reinecke <hare@suse.com> > Cc: Christoph Hellwig <hch@lst.de> > Cc: Andy Grover <agrover@redhat.com> > Cc: David Disseldorp <ddiss@suse.de> > --- I'm strongly opposed to adding another reference count and struct completion to every se_cmd, and using a special version of __target_put_sess_cmd() sprinkled all over the place. We've already got a se_cmd->cmd_kref, se_cmd->t_transport_stop_comp used for se_cmd quiesce (CMD_T_STOP) during CMD_T_ABORT and transport_generic_free_cmd() shutdown, and se_cmd->cmd_wait_set for drivers doing active I/O shutdown via target_sess_cmd_list_set_waiting. Adding a new reference count, a third struct completion, and fast path complete_all() for everyone (not just CMD_T_ABORT) just to get rid of se_cmd->cmd_wait_set doesn't simplify anything. So that said, dropping this patch until you can figure out how to use the single existing se_cmd->cmd_kref. > drivers/target/target_core_internal.h | 1 + > drivers/target/target_core_tmr.c | 8 ++++---- > drivers/target/target_core_transport.c | 24 +++++++++++++++++++++--- > include/target/target_core_base.h | 2 ++ > 4 files changed, 28 insertions(+), 7 deletions(-) > > diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h > index 9ab7090f7c83..48de996ad28d 100644 > --- a/drivers/target/target_core_internal.h > +++ b/drivers/target/target_core_internal.h > @@ -146,6 +146,7 @@ int transport_dump_vpd_assoc(struct t10_vpd *, unsigned char *, int); > int transport_dump_vpd_ident_type(struct t10_vpd *, unsigned char *, int); > int transport_dump_vpd_ident(struct t10_vpd *, unsigned char *, int); > void transport_clear_lun_ref(struct se_lun *); > +int __target_put_sess_cmd(struct se_cmd *se_cmd); > void transport_send_task_abort(struct se_cmd *); > sense_reason_t target_cmd_size_check(struct se_cmd *cmd, unsigned int size); > void target_qf_do_work(struct work_struct *work); > diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c > index 367799b4dde1..161c8b8482db 100644 > --- a/drivers/target/target_core_tmr.c > +++ b/drivers/target/target_core_tmr.c > @@ -188,7 +188,7 @@ void core_tmr_abort_task( > if (!tmr->tmr_dev && > transport_lookup_tmr_lun(tmr->task_cmd, > se_cmd->orig_fe_lun) < 0) { > - target_put_sess_cmd(se_cmd); > + __target_put_sess_cmd(se_cmd); > continue; > } > > @@ -199,7 +199,7 @@ void core_tmr_abort_task( > transport_wait_for_tasks(se_cmd); > > transport_cmd_finish_abort(se_cmd, true); > - target_put_sess_cmd(se_cmd); > + __target_put_sess_cmd(se_cmd); > > printk("ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for" > " ref_tag: %llu\n", ref_tag); > @@ -299,7 +299,7 @@ static void core_tmr_drain_tmr_list( > transport_wait_for_tasks(cmd); > > transport_cmd_finish_abort(cmd, 1); > - target_put_sess_cmd(cmd); > + __target_put_sess_cmd(cmd); > } > } > > @@ -398,7 +398,7 @@ static void core_tmr_drain_state_list( > transport_wait_for_tasks(cmd); > > core_tmr_handle_tas_abort(cmd, tas); > - target_put_sess_cmd(cmd); > + __target_put_sess_cmd(cmd); > } > } > > diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c > index 8f2169e92771..533b584c2806 100644 > --- a/drivers/target/target_core_transport.c > +++ b/drivers/target/target_core_transport.c > @@ -1217,6 +1217,7 @@ void transport_init_se_cmd( > init_completion(&cmd->cmd_wait_comp); > spin_lock_init(&cmd->t_state_lock); > kref_init(&cmd->cmd_kref); > + atomic_set(&cmd->tgt_ref, 1); > cmd->transport_state = CMD_T_DEV_ACTIVE; > > cmd->se_tfo = tfo; > @@ -2554,6 +2555,7 @@ int target_get_sess_cmd(struct se_cmd *se_cmd, bool ack_kref) > if (!kref_get_unless_zero(&se_cmd->cmd_kref)) > return -EINVAL; > > + atomic_inc(&se_cmd->tgt_ref); > se_cmd->se_cmd_flags |= SCF_ACK_KREF; > } > > @@ -2590,6 +2592,8 @@ static void target_release_cmd_kref(struct kref *kref) > unsigned long flags; > bool fabric_stop; > > + WARN_ON_ONCE(atomic_read(&se_cmd->tgt_ref) != 0); > + > if (se_sess) { > spin_lock_irqsave(&se_sess->sess_cmd_lock, flags); > > @@ -2614,15 +2618,29 @@ static void target_release_cmd_kref(struct kref *kref) > } > > /** > + * __target_put_sess_cmd - drop a reference obtained by kref_get_unless_zero() > + */ > +int __target_put_sess_cmd(struct se_cmd *se_cmd) > +{ > + return kref_put(&se_cmd->cmd_kref, target_release_cmd_kref); > +} > + > +/** > * target_put_sess_cmd - decrease the command reference count > - * @se_cmd: command to drop a reference from > + * @se_cmd: Drop a reference obtained by target_get_sess_cmd(). > * > * Returns 1 if and only if this target_put_sess_cmd() call caused the > * refcount to drop to zero. Returns zero otherwise. > */ > int target_put_sess_cmd(struct se_cmd *se_cmd) > { > - return kref_put(&se_cmd->cmd_kref, target_release_cmd_kref); > + long ref = atomic_dec_return(&se_cmd->tgt_ref); > + > + WARN_ON_ONCE(ref < 0); > + if (ref == 0) > + complete(&se_cmd->complete); > + > + return __target_put_sess_cmd(se_cmd); > } > EXPORT_SYMBOL(target_put_sess_cmd); > > @@ -2680,7 +2698,7 @@ void target_wait_for_sess_cmds(struct se_session *se_sess) > tas = (se_cmd->transport_state & CMD_T_TAS); > spin_unlock_irqrestore(&se_cmd->t_state_lock, flags); > > - if (!target_put_sess_cmd(se_cmd)) { > + if (!__target_put_sess_cmd(se_cmd)) { > if (tas) > target_put_sess_cmd(se_cmd); > } > diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h > index fb87f0e5d0d6..c84e5eecb94d 100644 > --- a/include/target/target_core_base.h > +++ b/include/target/target_core_base.h > @@ -495,7 +495,9 @@ struct se_cmd { > #define CMD_T_FABRIC_STOP (1 << 11) > spinlock_t t_state_lock; > struct kref cmd_kref; > + atomic_t tgt_ref; > struct completion t_transport_stop_comp; > + struct completion complete; > > struct work_struct work; > -- To unsubscribe from this list: send the line "unsubscribe target-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, 2017-02-09 at 08:06 +0100, Hannes Reinecke wrote: > On 02/08/2017 11:24 PM, Bart Van Assche wrote: > > This reference count keeps track of the number of references held > > by a target driver on a command. se_cmd.complete is set once the > > target driver has released all references it held on a command. > > > > Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> > > Cc: Hannes Reinecke <hare@suse.com> > > Cc: Christoph Hellwig <hch@lst.de> > > Cc: Andy Grover <agrover@redhat.com> > > Cc: David Disseldorp <ddiss@suse.de> > > --- > > drivers/target/target_core_internal.h | 1 + > > drivers/target/target_core_tmr.c | 8 ++++---- > > drivers/target/target_core_transport.c | 24 +++++++++++++++++++++--- > > include/target/target_core_base.h | 2 ++ > > 4 files changed, 28 insertions(+), 7 deletions(-) > > > > diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h > > index 9ab7090f7c83..48de996ad28d 100644 > > --- a/drivers/target/target_core_internal.h > > +++ b/drivers/target/target_core_internal.h > > @@ -146,6 +146,7 @@ int transport_dump_vpd_assoc(struct t10_vpd *, unsigned char *, int); > > int transport_dump_vpd_ident_type(struct t10_vpd *, unsigned char *, int); > > int transport_dump_vpd_ident(struct t10_vpd *, unsigned char *, int); > > void transport_clear_lun_ref(struct se_lun *); > > +int __target_put_sess_cmd(struct se_cmd *se_cmd); > > void transport_send_task_abort(struct se_cmd *); > > sense_reason_t target_cmd_size_check(struct se_cmd *cmd, unsigned int size); > > void target_qf_do_work(struct work_struct *work); > > diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c > > index 367799b4dde1..161c8b8482db 100644 > > --- a/drivers/target/target_core_tmr.c > > +++ b/drivers/target/target_core_tmr.c > > @@ -188,7 +188,7 @@ void core_tmr_abort_task( > > if (!tmr->tmr_dev && > > transport_lookup_tmr_lun(tmr->task_cmd, > > se_cmd->orig_fe_lun) < 0) { > > - target_put_sess_cmd(se_cmd); > > + __target_put_sess_cmd(se_cmd); > > continue; > > } > > > > @@ -199,7 +199,7 @@ void core_tmr_abort_task( > > transport_wait_for_tasks(se_cmd); > > > > transport_cmd_finish_abort(se_cmd, true); > > - target_put_sess_cmd(se_cmd); > > + __target_put_sess_cmd(se_cmd); > > > > printk("ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for" > > " ref_tag: %llu\n", ref_tag); > > @@ -299,7 +299,7 @@ static void core_tmr_drain_tmr_list( > > transport_wait_for_tasks(cmd); > > > > transport_cmd_finish_abort(cmd, 1); > > - target_put_sess_cmd(cmd); > > + __target_put_sess_cmd(cmd); > > } > > } > > > > @@ -398,7 +398,7 @@ static void core_tmr_drain_state_list( > > transport_wait_for_tasks(cmd); > > > > core_tmr_handle_tas_abort(cmd, tas); > > - target_put_sess_cmd(cmd); > > + __target_put_sess_cmd(cmd); > > } > > } > > > > diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c > > index 8f2169e92771..533b584c2806 100644 > > --- a/drivers/target/target_core_transport.c > > +++ b/drivers/target/target_core_transport.c > > @@ -1217,6 +1217,7 @@ void transport_init_se_cmd( > > init_completion(&cmd->cmd_wait_comp); > > spin_lock_init(&cmd->t_state_lock); > > kref_init(&cmd->cmd_kref); > > + atomic_set(&cmd->tgt_ref, 1); > > cmd->transport_state = CMD_T_DEV_ACTIVE; > > > > cmd->se_tfo = tfo; > > @@ -2554,6 +2555,7 @@ int target_get_sess_cmd(struct se_cmd *se_cmd, bool ack_kref) > > if (!kref_get_unless_zero(&se_cmd->cmd_kref)) > > return -EINVAL; > > > > + atomic_inc(&se_cmd->tgt_ref); > > se_cmd->se_cmd_flags |= SCF_ACK_KREF; > > } > > > > @@ -2590,6 +2592,8 @@ static void target_release_cmd_kref(struct kref *kref) > > unsigned long flags; > > bool fabric_stop; > > > > + WARN_ON_ONCE(atomic_read(&se_cmd->tgt_ref) != 0); > > + > > if (se_sess) { > > spin_lock_irqsave(&se_sess->sess_cmd_lock, flags); > > > > @@ -2614,15 +2618,29 @@ static void target_release_cmd_kref(struct kref *kref) > > } > > > > /** > > + * __target_put_sess_cmd - drop a reference obtained by kref_get_unless_zero() > > + */ > > +int __target_put_sess_cmd(struct se_cmd *se_cmd) > > +{ > > + return kref_put(&se_cmd->cmd_kref, target_release_cmd_kref); > > +} > > + > > +/** > > * target_put_sess_cmd - decrease the command reference count > > - * @se_cmd: command to drop a reference from > > + * @se_cmd: Drop a reference obtained by target_get_sess_cmd(). > > * > > * Returns 1 if and only if this target_put_sess_cmd() call caused the > > * refcount to drop to zero. Returns zero otherwise. > > */ > > int target_put_sess_cmd(struct se_cmd *se_cmd) > > { > > - return kref_put(&se_cmd->cmd_kref, target_release_cmd_kref); > > + long ref = atomic_dec_return(&se_cmd->tgt_ref); > > + > > + WARN_ON_ONCE(ref < 0); > > + if (ref == 0) > > + complete(&se_cmd->complete); > > + > > + return __target_put_sess_cmd(se_cmd); > > } > > EXPORT_SYMBOL(target_put_sess_cmd); > > > > @@ -2680,7 +2698,7 @@ void target_wait_for_sess_cmds(struct se_session *se_sess) > > tas = (se_cmd->transport_state & CMD_T_TAS); > > spin_unlock_irqrestore(&se_cmd->t_state_lock, flags); > > > > - if (!target_put_sess_cmd(se_cmd)) { > > + if (!__target_put_sess_cmd(se_cmd)) { > > if (tas) > > target_put_sess_cmd(se_cmd); > > } > > diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h > > index fb87f0e5d0d6..c84e5eecb94d 100644 > > --- a/include/target/target_core_base.h > > +++ b/include/target/target_core_base.h > > @@ -495,7 +495,9 @@ struct se_cmd { > > #define CMD_T_FABRIC_STOP (1 << 11) > > spinlock_t t_state_lock; > > struct kref cmd_kref; > > + atomic_t tgt_ref; > > struct completion t_transport_stop_comp; > > + struct completion complete; > > > > struct work_struct work; > > > > > > What a curious construct. > Why not a normal kref here? > Using an atomic here would make sense if you need to bail out if both > counters would be independent. > But as it stands the 'tgt_kref' _has_ to be '0' before the final call to > __target_put_sess_cmd() (otherwise you'll end up with a hanging > wait_for_completion). > Which means that the lifetime of 'tgt_kref' is bounded by the lifetime > of se_cmd, and we can just add a second kref there. Although that will result in more code, I will change the atomic_t into a kref_t. Bart.-- To unsubscribe from this list: send the line "unsubscribe target-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, 2017-02-09 at 02:07 -0800, Nicholas A. Bellinger wrote: > I'm strongly opposed to adding another reference count and struct > completion to every se_cmd, and using a special version of > __target_put_sess_cmd() sprinkled all over the place. > > We've already got a se_cmd->cmd_kref, se_cmd->t_transport_stop_comp used > for se_cmd quiesce (CMD_T_STOP) during CMD_T_ABORT and > transport_generic_free_cmd() shutdown, and se_cmd->cmd_wait_set for > drivers doing active I/O shutdown via target_sess_cmd_list_set_waiting. > > Adding a new reference count, a third struct completion, and fast path > complete_all() for everyone (not just CMD_T_ABORT) just to get rid of > se_cmd->cmd_wait_set doesn't simplify anything. > > So that said, dropping this patch until you can figure out how to use > the single existing se_cmd->cmd_kref. It is very ugly that there are multiple direct calls of .release_cmd() in the target code. That is just not acceptable. The only way to address this is by introducing a second reference count in struct se_cmd. We need one reference count to keep track of the lifetime of struct se_cmd and a second reference count to keep track of the number of references held by the target driver. Regarding t_transport_stop_comp: my plan is to remove that completion later on. Bart.-- To unsubscribe from this list: send the line "unsubscribe target-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h index 9ab7090f7c83..48de996ad28d 100644 --- a/drivers/target/target_core_internal.h +++ b/drivers/target/target_core_internal.h @@ -146,6 +146,7 @@ int transport_dump_vpd_assoc(struct t10_vpd *, unsigned char *, int); int transport_dump_vpd_ident_type(struct t10_vpd *, unsigned char *, int); int transport_dump_vpd_ident(struct t10_vpd *, unsigned char *, int); void transport_clear_lun_ref(struct se_lun *); +int __target_put_sess_cmd(struct se_cmd *se_cmd); void transport_send_task_abort(struct se_cmd *); sense_reason_t target_cmd_size_check(struct se_cmd *cmd, unsigned int size); void target_qf_do_work(struct work_struct *work); diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c index 367799b4dde1..161c8b8482db 100644 --- a/drivers/target/target_core_tmr.c +++ b/drivers/target/target_core_tmr.c @@ -188,7 +188,7 @@ void core_tmr_abort_task( if (!tmr->tmr_dev && transport_lookup_tmr_lun(tmr->task_cmd, se_cmd->orig_fe_lun) < 0) { - target_put_sess_cmd(se_cmd); + __target_put_sess_cmd(se_cmd); continue; } @@ -199,7 +199,7 @@ void core_tmr_abort_task( transport_wait_for_tasks(se_cmd); transport_cmd_finish_abort(se_cmd, true); - target_put_sess_cmd(se_cmd); + __target_put_sess_cmd(se_cmd); printk("ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for" " ref_tag: %llu\n", ref_tag); @@ -299,7 +299,7 @@ static void core_tmr_drain_tmr_list( transport_wait_for_tasks(cmd); transport_cmd_finish_abort(cmd, 1); - target_put_sess_cmd(cmd); + __target_put_sess_cmd(cmd); } } @@ -398,7 +398,7 @@ static void core_tmr_drain_state_list( transport_wait_for_tasks(cmd); core_tmr_handle_tas_abort(cmd, tas); - target_put_sess_cmd(cmd); + __target_put_sess_cmd(cmd); } } diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index 8f2169e92771..533b584c2806 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -1217,6 +1217,7 @@ void transport_init_se_cmd( init_completion(&cmd->cmd_wait_comp); spin_lock_init(&cmd->t_state_lock); kref_init(&cmd->cmd_kref); + atomic_set(&cmd->tgt_ref, 1); cmd->transport_state = CMD_T_DEV_ACTIVE; cmd->se_tfo = tfo; @@ -2554,6 +2555,7 @@ int target_get_sess_cmd(struct se_cmd *se_cmd, bool ack_kref) if (!kref_get_unless_zero(&se_cmd->cmd_kref)) return -EINVAL; + atomic_inc(&se_cmd->tgt_ref); se_cmd->se_cmd_flags |= SCF_ACK_KREF; } @@ -2590,6 +2592,8 @@ static void target_release_cmd_kref(struct kref *kref) unsigned long flags; bool fabric_stop; + WARN_ON_ONCE(atomic_read(&se_cmd->tgt_ref) != 0); + if (se_sess) { spin_lock_irqsave(&se_sess->sess_cmd_lock, flags); @@ -2614,15 +2618,29 @@ static void target_release_cmd_kref(struct kref *kref) } /** + * __target_put_sess_cmd - drop a reference obtained by kref_get_unless_zero() + */ +int __target_put_sess_cmd(struct se_cmd *se_cmd) +{ + return kref_put(&se_cmd->cmd_kref, target_release_cmd_kref); +} + +/** * target_put_sess_cmd - decrease the command reference count - * @se_cmd: command to drop a reference from + * @se_cmd: Drop a reference obtained by target_get_sess_cmd(). * * Returns 1 if and only if this target_put_sess_cmd() call caused the * refcount to drop to zero. Returns zero otherwise. */ int target_put_sess_cmd(struct se_cmd *se_cmd) { - return kref_put(&se_cmd->cmd_kref, target_release_cmd_kref); + long ref = atomic_dec_return(&se_cmd->tgt_ref); + + WARN_ON_ONCE(ref < 0); + if (ref == 0) + complete(&se_cmd->complete); + + return __target_put_sess_cmd(se_cmd); } EXPORT_SYMBOL(target_put_sess_cmd); @@ -2680,7 +2698,7 @@ void target_wait_for_sess_cmds(struct se_session *se_sess) tas = (se_cmd->transport_state & CMD_T_TAS); spin_unlock_irqrestore(&se_cmd->t_state_lock, flags); - if (!target_put_sess_cmd(se_cmd)) { + if (!__target_put_sess_cmd(se_cmd)) { if (tas) target_put_sess_cmd(se_cmd); } diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h index fb87f0e5d0d6..c84e5eecb94d 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -495,7 +495,9 @@ struct se_cmd { #define CMD_T_FABRIC_STOP (1 << 11) spinlock_t t_state_lock; struct kref cmd_kref; + atomic_t tgt_ref; struct completion t_transport_stop_comp; + struct completion complete; struct work_struct work;
This reference count keeps track of the number of references held by a target driver on a command. se_cmd.complete is set once the target driver has released all references it held on a command. Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Andy Grover <agrover@redhat.com> Cc: David Disseldorp <ddiss@suse.de> --- drivers/target/target_core_internal.h | 1 + drivers/target/target_core_tmr.c | 8 ++++---- drivers/target/target_core_transport.c | 24 +++++++++++++++++++++--- include/target/target_core_base.h | 2 ++ 4 files changed, 28 insertions(+), 7 deletions(-)