[PATCH v4 60/78] ncr5380: Implement new eh_abort_handler

Finn Thain
2016-01-03T05:18:27Z

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[-- Type: text/plain, Size: 12620 bytes --]

Introduce a new eh_abort_handler implementation. This one attempts to
follow all of the rules relating to EH handlers. There is still a known
bug: during selection, a command becomes invisible to the EH handlers
because it only appears in a pointer on the stack of a different thread.
This bug is addressed in a subsequent patch.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>

---
drivers/scsi/NCR5380.c | 155 ++++++++++++++++++++++++++++++++++++++----
drivers/scsi/atari_NCR5380.c | 157 ++++++++++++++++++++++++++++++++++++++-----
2 files changed, 282 insertions(+), 30 deletions(-)

Index: linux/drivers/scsi/atari_NCR5380.c
===================================================================
--- linux.orig/drivers/scsi/atari_NCR5380.c 2016-01-03 16:04:25.000000000 +1100
+++ linux/drivers/scsi/atari_NCR5380.c 2016-01-03 16:04:28.000000000 +1100
@@ -2480,41 +2480,168 @@ static void NCR5380_reselect(struct Scsi
}

-/*
- * Function : int NCR5380_abort (struct scsi_cmnd *cmd)
+/**
+ * list_find_cmd - test for presence of a command in a linked list
+ * @haystack: list of commands
+ * @needle: command to search for
+ */
+
+static bool list_find_cmd(struct list_head *haystack,
+ struct scsi_cmnd *needle)
+{
+ struct NCR5380_cmd *ncmd;
+
+ list_for_each_entry(ncmd, haystack, list)
+ if (NCR5380_to_scmd(ncmd) == needle)
+ return true;
+ return false;
+}
+
+/**
+ * list_remove_cmd - remove a command from linked list
+ * @haystack: list of commands
+ * @needle: command to remove
+ */
+
+static bool list_del_cmd(struct list_head *haystack,
+ struct scsi_cmnd *needle)
+{
+ if (list_find_cmd(haystack, needle)) {
+ struct NCR5380_cmd *ncmd = scsi_cmd_priv(needle);
+
+ list_del(&ncmd->list);
+ return true;
+ }
+ return false;
+}
+
+/**
+ * NCR5380_abort - scsi host eh_abort_handler() method
+ * @cmd: the command to be aborted
*
- * Purpose : abort a command
+ * Try to abort a given command by removing it from queues and/or sending
+ * the target an abort message. This may not succeed in causing a target
+ * to abort the command. Nonetheless, the low-level driver must forget about
+ * the command because the mid-layer reclaims it and it may be re-issued.
*
- * Inputs : cmd - the scsi_cmnd to abort, code - code to set the
- * host byte of the result field to, if zero DID_ABORTED is
- * used.
+ * The normal path taken by a command is as follows. For EH we trace this
+ * same path to locate and abort the command.
*
- * Returns : SUCCESS - success, FAILED on failure.
+ * unissued -> selecting -> [unissued -> selecting ->]... connected ->
+ * [disconnected -> connected ->]...
+ * [autosense -> connected ->] done
*
- * XXX - there is no way to abort the command that is currently
- * connected, you have to wait for it to complete. If this is
- * a problem, we could implement longjmp() / setjmp(), setjmp()
- * called where the loop started in NCR5380_main().
+ * If cmd is unissued then just remove it.
+ * If cmd is disconnected, try to select the target.
+ * If cmd is connected, try to send an abort message.
+ * If cmd is waiting for autosense, give it a chance to complete but check
+ * that it isn't left connected.
+ * If cmd was not found at all then presumably it has already been completed,
+ * in which case return SUCCESS to try to avoid further EH measures.
+ * If the command has not completed yet, we must not fail to find it.
*/

-static
-int NCR5380_abort(struct scsi_cmnd *cmd)
+static int NCR5380_abort(struct scsi_cmnd *cmd)
{
struct Scsi_Host *instance = cmd->device->host;
struct NCR5380_hostdata *hostdata = shost_priv(instance);
unsigned long flags;
+ int result = SUCCESS;

spin_lock_irqsave(&hostdata->lock, flags);

#if (NDEBUG & NDEBUG_ANY)
- scmd_printk(KERN_INFO, cmd, "aborting command\n");
+ scmd_printk(KERN_INFO, cmd, __func__);
#endif
NCR5380_dprint(NDEBUG_ANY, instance);
NCR5380_dprint_phase(NDEBUG_ANY, instance);

+ if (list_del_cmd(&hostdata->unissued, cmd)) {
+ dsprintk(NDEBUG_ABORT, instance,
+ "abort: removed %p from issue queue\n", cmd);
+ cmd->result = DID_ABORT << 16;
+ cmd->scsi_done(cmd); /* No tag or busy flag to worry about */
+ }
+
+ if (list_del_cmd(&hostdata->disconnected, cmd)) {
+ dsprintk(NDEBUG_ABORT, instance,
+ "abort: removed %p from disconnected list\n", cmd);
+ cmd->result = DID_ERROR << 16;
+ if (!hostdata->connected)
+ NCR5380_select(instance, cmd);
+ if (hostdata->connected != cmd) {
+ complete_cmd(instance, cmd);
+ result = FAILED;
+ goto out;
+ }
+ }
+
+ if (hostdata->connected == cmd) {
+ dsprintk(NDEBUG_ABORT, instance, "abort: cmd %p is connected\n", cmd);
+ hostdata->connected = NULL;
+ if (do_abort(instance)) {
+ set_host_byte(cmd, DID_ERROR);
+ complete_cmd(instance, cmd);
+ result = FAILED;
+ goto out;
+ }
+ set_host_byte(cmd, DID_ABORT);
+#ifdef REAL_DMA
+ hostdata->dma_len = 0;
+#endif
+ if (cmd->cmnd[0] == REQUEST_SENSE)
+ complete_cmd(instance, cmd);
+ else {
+ struct NCR5380_cmd *ncmd = scsi_cmd_priv(cmd);
+
+ /* Perform autosense for this command */
+ list_add(&ncmd->list, &hostdata->autosense);
+ }
+ }
+
+ if (list_find_cmd(&hostdata->autosense, cmd)) {
+ dsprintk(NDEBUG_ABORT, instance,
+ "abort: found %p on sense queue\n", cmd);
+ spin_unlock_irqrestore(&hostdata->lock, flags);
+ queue_work(hostdata->work_q, &hostdata->main_task);
+ msleep(1000);
+ spin_lock_irqsave(&hostdata->lock, flags);
+ if (list_del_cmd(&hostdata->autosense, cmd)) {
+ dsprintk(NDEBUG_ABORT, instance,
+ "abort: removed %p from sense queue\n", cmd);
+ set_host_byte(cmd, DID_ABORT);
+ complete_cmd(instance, cmd);
+ goto out;
+ }
+ }
+
+ if (hostdata->connected == cmd) {
+ dsprintk(NDEBUG_ABORT, instance, "abort: cmd %p is connected\n", cmd);
+ hostdata->connected = NULL;
+ if (do_abort(instance)) {
+ set_host_byte(cmd, DID_ERROR);
+ complete_cmd(instance, cmd);
+ result = FAILED;
+ goto out;
+ }
+ set_host_byte(cmd, DID_ABORT);
+#ifdef REAL_DMA
+ hostdata->dma_len = 0;
+#endif
+ complete_cmd(instance, cmd);
+ }
+
+out:
+ if (result == FAILED)
+ dsprintk(NDEBUG_ABORT, instance, "abort: failed to abort %p\n", cmd);
+ else
+ dsprintk(NDEBUG_ABORT, instance, "abort: successfully aborted %p\n", cmd);
+
+ queue_work(hostdata->work_q, &hostdata->main_task);
+ maybe_release_dma_irq(instance);
spin_unlock_irqrestore(&hostdata->lock, flags);

- return FAILED;
+ return result;
}

Index: linux/drivers/scsi/NCR5380.c
===================================================================
--- linux.orig/drivers/scsi/NCR5380.c 2016-01-03 16:04:25.000000000 +1100
+++ linux/drivers/scsi/NCR5380.c 2016-01-03 16:04:28.000000000 +1100
@@ -2269,23 +2269,65 @@ static void NCR5380_dma_complete(NCR5380
}
#endif /* def REAL_DMA */

-/*
- * Function : int NCR5380_abort (struct scsi_cmnd *cmd)
- *
- * Purpose : abort a command
+/**
+ * list_find_cmd - test for presence of a command in a linked list
+ * @haystack: list of commands
+ * @needle: command to search for
+ */
+
+static bool list_find_cmd(struct list_head *haystack,
+ struct scsi_cmnd *needle)
+{
+ struct NCR5380_cmd *ncmd;
+
+ list_for_each_entry(ncmd, haystack, list)
+ if (NCR5380_to_scmd(ncmd) == needle)
+ return true;
+ return false;
+}
+
+/**
+ * list_remove_cmd - remove a command from linked list
+ * @haystack: list of commands
+ * @needle: command to remove
+ */
+
+static bool list_del_cmd(struct list_head *haystack,
+ struct scsi_cmnd *needle)
+{
+ if (list_find_cmd(haystack, needle)) {
+ struct NCR5380_cmd *ncmd = scsi_cmd_priv(needle);
+
+ list_del(&ncmd->list);
+ return true;
+ }
+ return false;
+}
+
+/**
+ * NCR5380_abort - scsi host eh_abort_handler() method
+ * @cmd: the command to be aborted
*
- * Inputs : cmd - the scsi_cmnd to abort, code - code to set the
- * host byte of the result field to, if zero DID_ABORTED is
- * used.
+ * Try to abort a given command by removing it from queues and/or sending
+ * the target an abort message. This may not succeed in causing a target
+ * to abort the command. Nonetheless, the low-level driver must forget about
+ * the command because the mid-layer reclaims it and it may be re-issued.
*
- * Returns : SUCCESS - success, FAILED on failure.
+ * The normal path taken by a command is as follows. For EH we trace this
+ * same path to locate and abort the command.
*
- * XXX - there is no way to abort the command that is currently
- * connected, you have to wait for it to complete. If this is
- * a problem, we could implement longjmp() / setjmp(), setjmp()
- * called where the loop started in NCR5380_main().
+ * unissued -> selecting -> [unissued -> selecting ->]... connected ->
+ * [disconnected -> connected ->]...
+ * [autosense -> connected ->] done
*
- * Locks: host lock taken by caller
+ * If cmd is unissued then just remove it.
+ * If cmd is disconnected, try to select the target.
+ * If cmd is connected, try to send an abort message.
+ * If cmd is waiting for autosense, give it a chance to complete but check
+ * that it isn't left connected.
+ * If cmd was not found at all then presumably it has already been completed,
+ * in which case return SUCCESS to try to avoid further EH measures.
+ * If the command has not completed yet, we must not fail to find it.
*/

static int NCR5380_abort(struct scsi_cmnd *cmd)
@@ -2293,18 +2335,101 @@ static int NCR5380_abort(struct scsi_cmn
struct Scsi_Host *instance = cmd->device->host;
struct NCR5380_hostdata *hostdata = shost_priv(instance);
unsigned long flags;
+ int result = SUCCESS;

spin_lock_irqsave(&hostdata->lock, flags);

#if (NDEBUG & NDEBUG_ANY)
- scmd_printk(KERN_INFO, cmd, "aborting command\n");
+ scmd_printk(KERN_INFO, cmd, __func__);
#endif
NCR5380_dprint(NDEBUG_ANY, instance);
NCR5380_dprint_phase(NDEBUG_ANY, instance);

+ if (list_del_cmd(&hostdata->unissued, cmd)) {
+ dsprintk(NDEBUG_ABORT, instance,
+ "abort: removed %p from issue queue\n", cmd);
+ cmd->result = DID_ABORT << 16;
+ cmd->scsi_done(cmd); /* No tag or busy flag to worry about */
+ }
+
+ if (list_del_cmd(&hostdata->disconnected, cmd)) {
+ dsprintk(NDEBUG_ABORT, instance,
+ "abort: removed %p from disconnected list\n", cmd);
+ cmd->result = DID_ERROR << 16;
+ if (!hostdata->connected)
+ NCR5380_select(instance, cmd);
+ if (hostdata->connected != cmd) {
+ complete_cmd(instance, cmd);
+ result = FAILED;
+ goto out;
+ }
+ }
+
+ if (hostdata->connected == cmd) {
+ dsprintk(NDEBUG_ABORT, instance, "abort: cmd %p is connected\n", cmd);
+ hostdata->connected = NULL;
+ if (do_abort(instance)) {
+ set_host_byte(cmd, DID_ERROR);
+ complete_cmd(instance, cmd);
+ result = FAILED;
+ goto out;
+ }
+ set_host_byte(cmd, DID_ABORT);
+#ifdef REAL_DMA
+ hostdata->dma_len = 0;
+#endif
+ if (cmd->cmnd[0] == REQUEST_SENSE)
+ complete_cmd(instance, cmd);
+ else {
+ struct NCR5380_cmd *ncmd = scsi_cmd_priv(cmd);
+
+ /* Perform autosense for this command */
+ list_add(&ncmd->list, &hostdata->autosense);
+ }
+ }
+
+ if (list_find_cmd(&hostdata->autosense, cmd)) {
+ dsprintk(NDEBUG_ABORT, instance,
+ "abort: found %p on sense queue\n", cmd);
+ spin_unlock_irqrestore(&hostdata->lock, flags);
+ queue_work(hostdata->work_q, &hostdata->main_task);
+ msleep(1000);
+ spin_lock_irqsave(&hostdata->lock, flags);
+ if (list_del_cmd(&hostdata->autosense, cmd)) {
+ dsprintk(NDEBUG_ABORT, instance,
+ "abort: removed %p from sense queue\n", cmd);
+ set_host_byte(cmd, DID_ABORT);
+ complete_cmd(instance, cmd);
+ goto out;
+ }
+ }
+
+ if (hostdata->connected == cmd) {
+ dsprintk(NDEBUG_ABORT, instance, "abort: cmd %p is connected\n", cmd);
+ hostdata->connected = NULL;
+ if (do_abort(instance)) {
+ set_host_byte(cmd, DID_ERROR);
+ complete_cmd(instance, cmd);
+ result = FAILED;
+ goto out;
+ }
+ set_host_byte(cmd, DID_ABORT);
+#ifdef REAL_DMA
+ hostdata->dma_len = 0;
+#endif
+ complete_cmd(instance, cmd);
+ }
+
+out:
+ if (result == FAILED)
+ dsprintk(NDEBUG_ABORT, instance, "abort: failed to abort %p\n", cmd);
+ else
+ dsprintk(NDEBUG_ABORT, instance, "abort: successfully aborted %p\n", cmd);
+
+ queue_work(hostdata->work_q, &hostdata->main_task);
spin_unlock_irqrestore(&hostdata->lock, flags);

- return FAILED;
+ return result;
}