Hi Joe, >-----Original Message----- >From: Joe Lawrence [mailto:joe.lawrence@xxxxxxxxxxx] >Sent: Tuesday, July 16, 2013 8:52 PM >To: James Bottomley >Cc: Reddy, Sreekanth; linux-scsi@xxxxxxxxxxxxxxx >Subject: Re: mpt2sas,mpt3sas watchdog device removal > >On Tue, 16 Jul 2013 16:03:38 +0400 >James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: > >> On Tue, 2013-07-16 at 17:30 +0530, Reddy, Sreekanth wrote: >> > James, >> > >> > This patch seem to be fine. Please consider this patch. >> >> Where's the new version? The one that has all of this fixed: >> >> > Off list, Sreekanth from LSI tested and noticed a few issues with >> > this >> > patch: >> > >> > - mpt2sas_base_stop_watchdog is called twice: The call from >> > mpt2sas_base_detach is safe, but now unnecessary (as a call was >> > added earlier up in the PCI driver callbacks to ensure that the >> > watchdog was out of the way.) This second invocation can be >> > removed. >> > >> > - If the watchdog detects a bad IOC, the watchdog remains running: >> > The watchdog workqueue isn't cleaned up until >> > mpt2sas_base_stop_watchdog is called, so in the case that the >> > watchdog removes the device from SCSI topo, the workqueue will >> > remain unused until PCI .remove/.shutdown cleans it up. Perhaps a >> > single watchdog that iterates over all adapters would be simpler? >> > >> > Finally, if SCSI topo detachment is all that is interesting here, >> > would it make more sense to move the watchdog into the MPT "scsi" >> > code? I haven't looked at the code yet, but this might make an MPT >> > fusion patch easier (due to dependencies between its "scsi" and >> > "base" modules). > >This patch fizzled out in May as other work took priority. If LSI is still >interested in these changes, I can dust off my notes and test/rebase for the >3.11 series. It would be grate help if you post the updated patch which will accommodate the fixes for above comments. > >A few of the issues quoted above are easily fixed, however I remember >having an outstanding question of how to best clean up the driver's per device >watchdog workqueue: > >The way the MPT drivers are working right now is that the watchdog >workqueue function _base_fault_reset_work() initiates a PCI device removal >via kthread. The PCI callback kthread context then tears down the device and >cancel/flush/destroys the watchdog workqueue. > >This patch eliminated the kthread and its call into PCI API, simply detaching >from the SCSI midlayer. In my opinion, the kthread complicated device >removal and introduced potential races if the watchdog tried removing the >device at the same time an ordinary device removal request occurred. > >At the time, the best solution I had was to leave the unused workqueue >around until its PCI device was removed. > >Regards, > >-- Joe Regards, Sreekanth -- 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
