On Jun 25, 2013, at 10:31 AM, Bart Van Assche <bvanassche@xxxxxxx> wrote: > On 06/25/13 15:45, James Bottomley wrote: >> On Tue, 2013-06-25 at 11:01 +0200, Bart Van Assche wrote: >>> There is a difference though between moving the EH kthread_stop() call >>> and the patch at the start of this thread: moving the EH kthread_stop() >>> call does not prevent that an ioctl like SG_SCSI_RESET triggers an eh_* >>> callback after scsi_remove_host() has finished. However, the >>> scsi_begin_eh() / scsi_end_eh() functions do prevent that an ioctl can >>> cause an eh_* callback to be invoked after scsi_remove_device() finished. >> >> OK, but this doesn't tell me what you're trying to achieve. >> >> An eh function is allowable as long as the host hadn't had the release >> callback executed. That means you must have to have a reference to the >> device/host to execute the eh function, which is currently guaranteed >> for all invocations. > > That raises a new question: how is an LLD expected to clean up resources without triggering a race condition ? What you wrote means that it's not safe for an LLD to start cleaning up the resources needed by the eh_* callbacks immediately after scsi_remove_device() returns since it it not guaranteed that at that time all references to the device have already been dropped. > A callback in the device/target/host (whatever is needed) release function would do this right? If I understand James right, I think he suggested something like this in another mail. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
