diff options
| -rw-r--r-- | drivers/scsi/libfc/fc_exch.c | 131 | ||||
| -rw-r--r-- | include/scsi/libfc.h | 9 |
2 files changed, 101 insertions, 39 deletions
diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c index 47ebc7b..1b3a094 100644 --- a/drivers/scsi/libfc/fc_exch.c +++ b/drivers/scsi/libfc/fc_exch.c @@ -381,6 +381,8 @@ static void fc_exch_timer_set(struct fc_exch *ep, unsigned int timer_msec) /** * fc_exch_done_locked() - Complete an exchange with the exchange lock held * @ep: The exchange that is complete + * + * Note: May sleep if invoked from outside a response handler. */ static int fc_exch_done_locked(struct fc_exch *ep) { @@ -392,7 +394,6 @@ static int fc_exch_done_locked(struct fc_exch *ep) * ep, and in that case we only clear the resp and set it as * complete, so it can be reused by the timer to send the rrq. */ - ep->resp = NULL; if (ep->state & FC_EX_DONE) return rc; ep->esb_stat |= ESB_ST_COMPLETE; @@ -589,6 +590,8 @@ static struct fc_seq *fc_seq_start_next(struct fc_seq *sp) /* * Set the response handler for the exchange associated with a sequence. + * + * Note: May sleep if invoked from outside a response handler. */ static void fc_seq_set_resp(struct fc_seq *sp, void (*resp)(struct fc_seq *, struct fc_frame *, @@ -596,8 +599,18 @@ static void fc_seq_set_resp(struct fc_seq *sp, void *arg) { struct fc_exch *ep = fc_seq_exch(sp); + DEFINE_WAIT(wait); spin_lock_bh(&ep->ex_lock); + while (ep->resp_active && ep->resp_task != current) { + prepare_to_wait(&ep->resp_wq, &wait, TASK_UNINTERRUPTIBLE); + spin_unlock_bh(&ep->ex_lock); + + schedule(); + + spin_lock_bh(&ep->ex_lock); + } + finish_wait(&ep->resp_wq, &wait); ep->resp = resp; ep->arg = arg; spin_unlock_bh(&ep->ex_lock); @@ -681,6 +694,61 @@ static int fc_seq_exch_abort(const struct fc_seq *req_sp, } /** + * fc_invoke_resp() - invoke ep->resp() + * + * Notes: + * It is assumed that after initialization finished (this means the + * first unlock of ex_lock after fc_exch_alloc()) ep->resp and ep->arg are + * modified only via fc_seq_set_resp(). This guarantees that none of these + * two variables changes if ep->resp_active > 0. + * + * If an fc_seq_set_resp() call is busy modifying ep->resp and ep->arg when + * this function is invoked, the first spin_lock_bh() call in this function + * will wait until fc_seq_set_resp() has finished modifying these variables. + * + * Since fc_exch_done() invokes fc_seq_set_resp() it is guaranteed that that + * ep->resp() won't be invoked after fc_exch_done() has returned. + * + * The response handler itself may invoke fc_exch_done(), which will clear the + * ep->resp pointer. + * + * Return value: + * Returns true if and only if ep->resp has been invoked. + */ +static bool fc_invoke_resp(struct fc_exch *ep, struct fc_seq *sp, + struct fc_frame *fp) +{ + void (*resp)(struct fc_seq *, struct fc_frame *fp, void *arg); + void *arg; + bool res = false; + + spin_lock_bh(&ep->ex_lock); + ep->resp_active++; + if (ep->resp_task != current) + ep->resp_task = !ep->resp_task ? current : NULL; + resp = ep->resp; + arg = ep->arg; + spin_unlock_bh(&ep->ex_lock); + + if (resp) { + resp(sp, fp, arg); + res = true; + } else if (!IS_ERR(fp)) { + fc_frame_free(fp); + } + + spin_lock_bh(&ep->ex_lock); + if (--ep->resp_active == 0) + ep->resp_task = NULL; + spin_unlock_bh(&ep->ex_lock); + + if (ep->resp_active == 0) + wake_up(&ep->resp_wq); + + return res; +} + +/** * fc_exch_timeout() - Handle exchange timer expiration * @work: The work_struct identifying the exchange that timed out */ @@ -689,8 +757,6 @@ static void fc_exch_timeout(struct work_struct *work) struct fc_exch *ep = container_of(work, struct fc_exch, timeout_work.work); struct fc_seq *sp = &ep->seq; - void (*resp)(struct fc_seq *, struct fc_frame *fp, void *arg); - void *arg; u32 e_stat; int rc = 1; @@ -708,16 +774,13 @@ static void fc_exch_timeout(struct work_struct *work) fc_exch_rrq(ep); goto done; } else { - resp = ep->resp; - arg = ep->arg; - ep->resp = NULL; if (e_stat & ESB_ST_ABNORMAL) rc = fc_exch_done_locked(ep); spin_unlock_bh(&ep->ex_lock); if (!rc) fc_exch_delete(ep); - if (resp) - resp(sp, ERR_PTR(-FC_EX_TIMEOUT), arg); + fc_invoke_resp(ep, sp, ERR_PTR(-FC_EX_TIMEOUT)); + fc_seq_set_resp(sp, NULL, ep->arg); fc_seq_exch_abort(sp, 2 * ep->r_a_tov); goto done; } @@ -804,6 +867,8 @@ hit: ep->f_ctl = FC_FC_FIRST_SEQ; /* next seq is first seq */ ep->rxid = FC_XID_UNKNOWN; ep->class = mp->class; + ep->resp_active = 0; + init_waitqueue_head(&ep->resp_wq); INIT_DELAYED_WORK(&ep->timeout_work, fc_exch_timeout); out: return ep; @@ -864,6 +929,8 @@ static struct fc_exch *fc_exch_find(struct fc_exch_mgr *mp, u16 xid) * fc_exch_done() - Indicate that an exchange/sequence tuple is complete and * the memory allocated for the related objects may be freed. * @sp: The sequence that has completed + * + * Note: May sleep if invoked from outside a response handler. */ static void fc_exch_done(struct fc_seq *sp) { @@ -873,6 +940,8 @@ static void fc_exch_done(struct fc_seq *sp) spin_lock_bh(&ep->ex_lock); rc = fc_exch_done_locked(ep); spin_unlock_bh(&ep->ex_lock); + + fc_seq_set_resp(sp, NULL, ep->arg); if (!rc) fc_exch_delete(ep); } @@ -1436,9 +1505,7 @@ static void fc_exch_recv_req(struct fc_lport *lport, struct fc_exch_mgr *mp, * If new exch resp handler is valid then call that * first. */ - if (ep->resp) - ep->resp(sp, fp, ep->arg); - else + if (!fc_invoke_resp(ep, sp, fp)) lport->tt.lport_recv(lport, fp); fc_exch_release(ep); /* release from lookup */ } else { @@ -1462,8 +1529,6 @@ static void fc_exch_recv_seq_resp(struct fc_exch_mgr *mp, struct fc_frame *fp) struct fc_exch *ep; enum fc_sof sof; u32 f_ctl; - void (*resp)(struct fc_seq *, struct fc_frame *fp, void *arg); - void *ex_resp_arg; int rc; ep = fc_exch_find(mp, ntohs(fh->fh_ox_id)); @@ -1506,14 +1571,11 @@ static void fc_exch_recv_seq_resp(struct fc_exch_mgr *mp, struct fc_frame *fp) if (fc_sof_needs_ack(sof)) fc_seq_send_ack(sp, fp); - resp = ep->resp; - ex_resp_arg = ep->arg; if (fh->fh_type != FC_TYPE_FCP && fr_eof(fp) == FC_EOF_T && (f_ctl & (FC_FC_LAST_SEQ | FC_FC_END_SEQ)) == (FC_FC_LAST_SEQ | FC_FC_END_SEQ)) { spin_lock_bh(&ep->ex_lock); - resp = ep->resp; rc = fc_exch_done_locked(ep); WARN_ON(fc_seq_exch(sp) != ep); spin_unlock_bh(&ep->ex_lock); @@ -1534,10 +1596,8 @@ static void fc_exch_recv_seq_resp(struct fc_exch_mgr *mp, struct fc_frame *fp) * If new exch resp handler is valid then call that * first. */ - if (resp) - resp(sp, fp, ex_resp_arg); - else - fc_frame_free(fp); + fc_invoke_resp(ep, sp, fp); + fc_exch_release(ep); return; rel: @@ -1576,8 +1636,6 @@ static void fc_exch_recv_resp(struct fc_exch_mgr *mp, struct fc_frame *fp) */ static void fc_exch_abts_resp(struct fc_exch *ep, struct fc_frame *fp) { - void (*resp)(struct fc_seq *, struct fc_frame *fp, void *arg); - void *ex_resp_arg; struct fc_frame_header *fh; struct fc_ba_acc *ap; struct fc_seq *sp; @@ -1622,9 +1680,6 @@ static void fc_exch_abts_resp(struct fc_exch *ep, struct fc_frame *fp) break; } - resp = ep->resp; - ex_resp_arg = ep->arg; - /* do we need to do some other checks here. Can we reuse more of * fc_exch_recv_seq_resp */ @@ -1636,17 +1691,14 @@ static void fc_exch_abts_resp(struct fc_exch *ep, struct fc_frame *fp) ntoh24(fh->fh_f_ctl) & FC_FC_LAST_SEQ) rc = fc_exch_done_locked(ep); spin_unlock_bh(&ep->ex_lock); + + fc_exch_hold(ep); if (!rc) fc_exch_delete(ep); - - if (resp) - resp(sp, fp, ex_resp_arg); - else - fc_frame_free(fp); - + fc_invoke_resp(ep, sp, fp); if (has_rec) fc_exch_timer_set(ep, ep->r_a_tov); - + fc_exch_release(ep); } /** @@ -1768,32 +1820,33 @@ static void fc_seq_ls_rjt(struct fc_frame *rx_fp, enum fc_els_rjt_reason reason, /** * fc_exch_reset() - Reset an exchange * @ep: The exchange to be reset + * + * Note: May sleep if invoked from outside a response handler. */ static void fc_exch_reset(struct fc_exch *ep) { struct fc_seq *sp; - void (*resp)(struct fc_seq *, struct fc_frame *, void *); - void *arg; int rc = 1; spin_lock_bh(&ep->ex_lock); fc_exch_abort_locked(ep, 0); ep->state |= FC_EX_RST_CLEANUP; fc_exch_timer_cancel(ep); - resp = ep->resp; - ep->resp = NULL; if (ep->esb_stat & ESB_ST_REC_QUAL) atomic_dec(&ep->ex_refcnt); /* drop hold for rec_qual */ ep->esb_stat &= ~ESB_ST_REC_QUAL; - arg = ep->arg; sp = &ep->seq; rc = fc_exch_done_locked(ep); spin_unlock_bh(&ep->ex_lock); + + fc_exch_hold(ep); + if (!rc) fc_exch_delete(ep); - if (resp) - resp(sp, ERR_PTR(-FC_EX_CLOSED), arg); + fc_invoke_resp(ep, sp, ERR_PTR(-FC_EX_CLOSED)); + fc_seq_set_resp(sp, NULL, ep->arg); + fc_exch_release(ep); } /** diff --git a/include/scsi/libfc.h b/include/scsi/libfc.h index e1379b4..52beadf 100644 --- a/include/scsi/libfc.h +++ b/include/scsi/libfc.h @@ -410,6 +410,12 @@ struct fc_seq { * @fh_type: The frame type * @class: The class of service * @seq: The sequence in use on this exchange + * @resp_active: Number of tasks that are concurrently executing @resp(). + * @resp_task: If @resp_active > 0, either the task executing @resp(), the + * task that has been interrupted to execute the soft-IRQ + * executing @resp() or NULL if more than one task is executing + * @resp concurrently. + * @resp_wq: Waitqueue for the tasks waiting on @resp_active. * @resp: Callback for responses on this exchange * @destructor: Called when destroying the exchange * @arg: Passed as a void pointer to the resp() callback @@ -441,6 +447,9 @@ struct fc_exch { u32 r_a_tov; u32 f_ctl; struct fc_seq seq; + int resp_active; + struct task_struct *resp_task; + wait_queue_head_t resp_wq; void (*resp)(struct fc_seq *, struct fc_frame *, void *); void *arg; void (*destructor)(struct fc_seq *, void *); |
