Tejun Heo wrote:
ATA devices in SLEEP mode don't respond to any commands. SRST is necessary to wake it up. Till now, when a command is issued to a device in SLEEP mode, the command times out, which makes EH reset the device and retry the command after that, causing a long delay. This patch makes libata track SLEEP state and issue SRST automatically if a command is about to be issued to a device in SLEEP. Signed-off-by: Tejun Heo <htejun@xxxxxxxxx> Cc: Bruce Allen <ballen@xxxxxxxxxxxxxxxxxxxx> Cc: Andrew Paprocki <andrew@xxxxxxxxxxx> --- This patch is against #upstream + relocate-and-fix-post-command-processing patch (http://article.gmane.org/gmane.linux.ide/24001) The infinite loop with the previous patch wasn't caused by bug in sleep state tracking. It was happening because post-command processing was being performed for commands which are being retried from EH, so what happened was. 1. device is flagged SLEEPING 2. SLEEP is issued, as device is sleeping, EH is rescheduled against the qc for SLEEP. 3. EH kicks in and wakes up the device and clears SLEEPING. 4. EH finishes up failed qc which triggers post-command processing and sets SLEEPING. 5. SCSI command is retried, go back to #2. relocate-and-fix-post-command-processing patch fixes the original bug in post-command processing and this patch doesn't cause infinite loop anymore. drivers/ata/libata-core.c | 12 ++++++++++++ drivers/ata/libata-eh.c | 4 +++- include/linux/ata.h | 1 + include/linux/libata.h | 1 + 4 files changed, 17 insertions(+), 1 deletion(-)
applied, both of these changes were nice improvements, as well as fixing problems
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