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    Subject[PATCH 4.5 043/238] ncr5380: Call scsi_eh_prep_cmnd() and scsi_eh_restore_cmnd() as and when appropriate
    Date
    4.5-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Finn Thain <fthain@telegraphics.com.au>

    commit 8d5dbec3bcb24a7d071962448e0fecaca8c75cc7 upstream.

    This bug causes the wrong command to have its sense pointer overwritten,
    which sometimes leads to a NULL pointer deref. Fix this by checking which
    command is being requeued before restoring the scsi_eh_save data.

    It turns out that some targets will disconnect a REQUEST SENSE command.
    The autosense algorithm doesn't anticipate this. Hence multiple commands
    can end up undergoing autosense simultaneously, and they will all try to
    use the same scsi_eh_save struct, which won't work. Defer autosense when
    the scsi_eh_save storage is in use by another command.

    Fixes: f27db8eb98a1 ("ncr5380: Fix autosense bugs")
    Reported-and-tested-by: Michael Schmitz <schmitzmic@gmail.com>
    Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
    Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/scsi/NCR5380.c | 4 ++--
    drivers/scsi/atari_NCR5380.c | 4 ++--
    2 files changed, 4 insertions(+), 4 deletions(-)

    --- a/drivers/scsi/NCR5380.c
    +++ b/drivers/scsi/NCR5380.c
    @@ -760,7 +760,7 @@ static struct scsi_cmnd *dequeue_next_cm
    struct NCR5380_cmd *ncmd;
    struct scsi_cmnd *cmd;

    - if (list_empty(&hostdata->autosense)) {
    + if (hostdata->sensing || list_empty(&hostdata->autosense)) {
    list_for_each_entry(ncmd, &hostdata->unissued, list) {
    cmd = NCR5380_to_scmd(ncmd);
    dsprintk(NDEBUG_QUEUES, instance, "dequeue: cmd=%p target=%d busy=0x%02x lun=%llu\n",
    @@ -793,7 +793,7 @@ static void requeue_cmd(struct Scsi_Host
    struct NCR5380_hostdata *hostdata = shost_priv(instance);
    struct NCR5380_cmd *ncmd = scsi_cmd_priv(cmd);

    - if (hostdata->sensing) {
    + if (hostdata->sensing == cmd) {
    scsi_eh_restore_cmnd(cmd, &hostdata->ses);
    list_add(&ncmd->list, &hostdata->autosense);
    hostdata->sensing = NULL;
    --- a/drivers/scsi/atari_NCR5380.c
    +++ b/drivers/scsi/atari_NCR5380.c
    @@ -862,7 +862,7 @@ static struct scsi_cmnd *dequeue_next_cm
    struct NCR5380_cmd *ncmd;
    struct scsi_cmnd *cmd;

    - if (list_empty(&hostdata->autosense)) {
    + if (hostdata->sensing || list_empty(&hostdata->autosense)) {
    list_for_each_entry(ncmd, &hostdata->unissued, list) {
    cmd = NCR5380_to_scmd(ncmd);
    dsprintk(NDEBUG_QUEUES, instance, "dequeue: cmd=%p target=%d busy=0x%02x lun=%llu\n",
    @@ -901,7 +901,7 @@ static void requeue_cmd(struct Scsi_Host
    struct NCR5380_hostdata *hostdata = shost_priv(instance);
    struct NCR5380_cmd *ncmd = scsi_cmd_priv(cmd);

    - if (hostdata->sensing) {
    + if (hostdata->sensing == cmd) {
    scsi_eh_restore_cmnd(cmd, &hostdata->ses);
    list_add(&ncmd->list, &hostdata->autosense);
    hostdata->sensing = NULL;

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