linux/drivers/target/iscsi/iscsi_target_util.h
Roland Dreier d5627acba9 iscsi-target: Fix missed wakeup race in TX thread
The sleeping code in iscsi_target_tx_thread() is susceptible to the classic
missed wakeup race:

 - TX thread finishes handle_immediate_queue() and handle_response_queue(),
   thinks both queues are empty.
 - Another thread adds a queue entry and does wake_up_process(), which does
   nothing because the TX thread is still awake.
 - TX thread does schedule_timeout() and sleeps forever.

In practice this can kill an iSCSI connection if for example an initiator
does single-threaded writes and the target misses the wakeup window when
queueing an R2T; in this case the connection will be stuck until the
initiator loses patience and does some task management operation (or kills
the connection entirely).

Fix this by converting to wait_event_interruptible(), which does not
suffer from this sort of race.

Signed-off-by: Roland Dreier <roland@purestorage.com>
Cc: Andy Grover <agrover@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2012-11-01 00:38:44 -07:00

59 lines
3.7 KiB
C

#ifndef ISCSI_TARGET_UTIL_H
#define ISCSI_TARGET_UTIL_H
#define MARKER_SIZE 8
extern int iscsit_add_r2t_to_list(struct iscsi_cmd *, u32, u32, int, u32);
extern struct iscsi_r2t *iscsit_get_r2t_for_eos(struct iscsi_cmd *, u32, u32);
extern struct iscsi_r2t *iscsit_get_r2t_from_list(struct iscsi_cmd *);
extern void iscsit_free_r2t(struct iscsi_r2t *, struct iscsi_cmd *);
extern void iscsit_free_r2ts_from_list(struct iscsi_cmd *);
extern struct iscsi_cmd *iscsit_allocate_cmd(struct iscsi_conn *, gfp_t);
extern struct iscsi_seq *iscsit_get_seq_holder_for_datain(struct iscsi_cmd *, u32);
extern struct iscsi_seq *iscsit_get_seq_holder_for_r2t(struct iscsi_cmd *);
extern struct iscsi_r2t *iscsit_get_holder_for_r2tsn(struct iscsi_cmd *, u32);
int iscsit_sequence_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd, __be32 cmdsn);
extern int iscsit_check_unsolicited_dataout(struct iscsi_cmd *, unsigned char *);
extern struct iscsi_cmd *iscsit_find_cmd_from_itt(struct iscsi_conn *, itt_t);
extern struct iscsi_cmd *iscsit_find_cmd_from_itt_or_dump(struct iscsi_conn *,
itt_t, u32);
extern struct iscsi_cmd *iscsit_find_cmd_from_ttt(struct iscsi_conn *, u32);
extern int iscsit_find_cmd_for_recovery(struct iscsi_session *, struct iscsi_cmd **,
struct iscsi_conn_recovery **, itt_t);
extern void iscsit_add_cmd_to_immediate_queue(struct iscsi_cmd *, struct iscsi_conn *, u8);
extern struct iscsi_queue_req *iscsit_get_cmd_from_immediate_queue(struct iscsi_conn *);
extern void iscsit_add_cmd_to_response_queue(struct iscsi_cmd *, struct iscsi_conn *, u8);
extern struct iscsi_queue_req *iscsit_get_cmd_from_response_queue(struct iscsi_conn *);
extern void iscsit_remove_cmd_from_tx_queues(struct iscsi_cmd *, struct iscsi_conn *);
extern bool iscsit_conn_all_queues_empty(struct iscsi_conn *);
extern void iscsit_free_queue_reqs_for_conn(struct iscsi_conn *);
extern void iscsit_release_cmd(struct iscsi_cmd *);
extern void iscsit_free_cmd(struct iscsi_cmd *);
extern int iscsit_check_session_usage_count(struct iscsi_session *);
extern void iscsit_dec_session_usage_count(struct iscsi_session *);
extern void iscsit_inc_session_usage_count(struct iscsi_session *);
extern int iscsit_set_sync_and_steering_values(struct iscsi_conn *);
extern struct iscsi_conn *iscsit_get_conn_from_cid(struct iscsi_session *, u16);
extern struct iscsi_conn *iscsit_get_conn_from_cid_rcfr(struct iscsi_session *, u16);
extern void iscsit_check_conn_usage_count(struct iscsi_conn *);
extern void iscsit_dec_conn_usage_count(struct iscsi_conn *);
extern void iscsit_inc_conn_usage_count(struct iscsi_conn *);
extern void iscsit_mod_nopin_response_timer(struct iscsi_conn *);
extern void iscsit_start_nopin_response_timer(struct iscsi_conn *);
extern void iscsit_stop_nopin_response_timer(struct iscsi_conn *);
extern void __iscsit_start_nopin_timer(struct iscsi_conn *);
extern void iscsit_start_nopin_timer(struct iscsi_conn *);
extern void iscsit_stop_nopin_timer(struct iscsi_conn *);
extern int iscsit_send_tx_data(struct iscsi_cmd *, struct iscsi_conn *, int);
extern int iscsit_fe_sendpage_sg(struct iscsi_cmd *, struct iscsi_conn *);
extern int iscsit_tx_login_rsp(struct iscsi_conn *, u8, u8);
extern void iscsit_print_session_params(struct iscsi_session *);
extern int iscsit_print_dev_to_proc(char *, char **, off_t, int);
extern int iscsit_print_sessions_to_proc(char *, char **, off_t, int);
extern int iscsit_print_tpg_to_proc(char *, char **, off_t, int);
extern int rx_data(struct iscsi_conn *, struct kvec *, int, int);
extern int tx_data(struct iscsi_conn *, struct kvec *, int, int);
extern void iscsit_collect_login_stats(struct iscsi_conn *, u8, u8);
extern struct iscsi_tiqn *iscsit_snmp_get_tiqn(struct iscsi_conn *);
#endif /*** ISCSI_TARGET_UTIL_H ***/