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Tejun Heo authored
Originally, whole reset processing was done while the port is frozen and SError was cleared during @postreset(). This had two race conditions. 1: hotplug could occur after reset but before SError is cleared and libata won't know about it. 2: hotplug could occur after all the reset is complete but before the port is thawed. As all events are cleared on thaw, the hotplug event would be lost. Commit ac371987 kills the first race by clearing SError during link resume but before link onlineness test. However, this doesn't fix race #2 and in some cases clearing SError after SRST is a good idea. This patch solves this problem by cross checking link onlineness with classification result after SError is cleared and port is thawed. Reset is retried if link is online but all devices attached to the link are unknown. As all devices will be revalidated, this one-way check is enough to ensure that all devices are detected and revalidated reliably. This, luckily, also fixes the cases where host controller returns bogus status while harddrive is spinning up after hotplug making classification run before the device sends the first FIS and thus causes misdetection. Low level drivers can bypass the logic by setting class explicitly to ATA_DEV_NONE if ever necessary (currently none requires this). Signed-off-by:
Tejun Heo <htejun@gmail.com> Signed-off-by:
Jeff Garzik <jgarzik@redhat.com>
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