On Wed, Sep 12, 2018 at 03:31:07PM +0530, Sreekanth Reddy wrote: > On Wed, Sep 5, 2018 at 1:08 PM, Lukas Wunner <lukas@xxxxxxxxx> wrote: > > On Wed, Sep 05, 2018 at 11:45:45AM +0530, Sreekanth Reddy wrote: > > > I have one more instance where still we need this poll kthread, i.e > > > during the device probe time we have some commands which has more > > > timeout value (e.g. 300 seconds), so if user has unplugged this device > > > just after sending this more time-out valued command then driver has > > > to wait until this time-out value expires. i.e. this device is still > > > visible in lspci output until this 300 seconds timeout value expires > > > even though device is unplugged. if we have a poll kthread (which will > > > poll for every one second) then driver can early detect the unplugged > > > state and can terminate the outstanding commands and hence probe > > > operation can be completed quickly. > > > > The only instances I can see in your driver where it waits for 300 s > > is in _base_diag_reset(), which does an msleep(256) in a loop for up > > to 300 s, and scsih_scan_finished(), which is called in a loop with an > > msleep(10) by do_scsi_scan_host(). > > > > Any harm in simply checking for removal of the device in those loops > > and bailing out if so? Instead of the poll kthread to achieve the same? > > we can do for this port enable request but still we have other > requests where we don't have this type of loops and used > wait_for_completion_timeout () API where we can't bailout the request > in-between and we have to wait until the timeout value expires. For > these types of request terminating it though watchdog thread will be > simple. When the HBA is hot-removed, its driver's ->remove callback is invoked. You could just check at the beginning of the ->remove callback whether the device is no longer present, and if it isn't, complete() any completions that may be pending. I think that would obviate the need for a watchdog. Thanks, Lukas
