hi all:
I am writing a thread and it will call sd_check_events per 1 second.
1. before system goes to hibernate, the thread works fine
2. system hibernate and restore back.
3. udev->state will keep USB_STATE_SUSPENDED before finish_port_resume
4. during above 2) and 3) sd_check_events keep polling but get
transport error and call usb_stor_port_reset.
since udev->state is USB_STATE_SUSPENDED, the usb_stor_port_reset
will fail due to unable lock device for reset (error = -113)
5. in finish_port_resume, it first change udev->state as
USB_STATE_CONFIGURED or USB_STATE_ADDRESS. then call
usb_reset_and_verify_device like below:
usb_set_device_state(udev, udev->actconfig
? USB_STATE_CONFIGURED
: USB_STATE_ADDRESS);
/* 10.5.4.5 says not to reset a suspended port if the attached
* device is enabled for remote wakeup. Hence the reset
* operation is carried out here, after the port has been
* resumed.
*/
if (udev->reset_resume)
retry_reset_resume:
status = usb_reset_and_verify_device(udev);
6. usb_reset_and_verify_device will call hub_port_init
7. usb_reset_and_verify_device will call descriptors_changed,
8. if sd_check_events polling again in during 6) and 7),
descriptors_changed may return true and report port resume fail.
My questions are:
a. is there any system flag such suspend/resume in scsi layer for
checking before sending command to downlayer driver, such as usb.
b. shall we add other flag in usb_stor_port_reset to make sure above
race condition will not happen?
appreciate your kind help,
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