On Saturday 12 September 2009, Pavel Machek wrote: > On Sat 2009-09-12 00:04:02, Rafael J. Wysocki wrote: > > On Friday 11 September 2009, OGAWA Hirofumi wrote: > > > Pavel Machek <pavel@xxxxxx> writes: > > > > > > > On Wed 2009-09-09 22:21:56, OGAWA Hirofumi wrote: > > > >> Pavel Machek <pavel@xxxxxx> writes: > > > >> > > > >> >> It seems > > > >> >> > > > >> >> 1) sync() (probabry "sync" command) > > > >> >> 2) sync as part of suspend sequence > > > >> >> 3) sync_filesystem() by mmc remove event > > > >> >> > > > >> >> I guess the root-cause of the problem would be 3). However, it would not > > > >> >> be easy to fix, at least, we would need to think about what we want to > > > >> >> do for it. So, to workaround it for now, I've made this patch. > > > >> > > > > >> > MMC driver trying to synchronize filesystems looks like ugly layering > > > >> > violation to me. Why are we doing that? > > > >> > > > >> There is no _layering violation_ here. IIRC, mmc just tells card removed > > > >> event to another layer (on some points of view, to tell event can be > > > >> wrong though). The partition (block) layer does it by event. > > > > > > > > So what is the problem? Emulating sync when card is already removed > > > > seems little ... interesting? > > > > > > Um..., sorry, I'm not sure what are you talking about. Of course, the > > > problem of this is that system freeze on suspend. > > > > > > Or are you asking my guess of the cause, or something? If so, although > > > I'm not reading all emails on this thread, from Zdenek's backtrace, the > > > sequence would be > > > > > > 1) suspend mmc > > > 2) mmc generates card removed event > > > > Which shouldn't happen. > > Are you sure? IIRC it depends on CONFIG_MMC_UNSAFE_RESUME. Generating the event at this point is too late, because there's no way to handle it cleanly with the current suspend/resume design. It probably will work if the event is generated before we freeze the user space, for example with the help of a suspend notifier, but generating it from a driver's suspend routine is not valid. Again, that's a consequence of the lack of a general solution for handling "removable" file systems over suspend/resume. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
