Messages in this thread | | | Date | Thu, 17 May 2007 09:43:00 +0530 | From | "Satyam Sharma" <> | Subject | Re: [PATCH] make hci_notifier a blocking notifier (was Re: BUG: sleeping function called from invalid context at net/core/sock.c:1523) |
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On 5/17/07, Ray Lee <ray-lk@madrabbit.org> wrote: > Apologies for taking so long to get back to you -- I've been on the > road for the last week and have finally got to a point where I could > test the patch. > > On 5/6/07, Satyam Sharma <satyam.sharma@gmail.com> wrote: > > (Dropped Pavel, Rafael and linux-pm from CC list, this isn't a PM > > error so don't want to spam them; and added bluez-devel) > > > > On 5/7/07, Ray Lee <ray-lk@madrabbit.org> wrote: > > > On 5/6/07, Alan Stern <stern@rowland.harvard.edu> wrote: > > > > On Sun, 6 May 2007, Satyam Sharma wrote: > > > > > > > > > Anyway, the hci_notifier is called from the following six call sites: > > > > > > > > > > hci_dev_open() and hci_dev_close() -> both called from > > > > > hci_sock_ioctl() => both can sleep > > > > > hci_register_dev() and hci_unregister_dev() => again both are capable > > > > > of sleeping > > > > > hci_suspend_dev() and hci_resume_dev() -> called from the .suspend() > > > > > and .resume() of the hci_usb_driver, and again both of these can sleep > > > > > > > > > > Is there any other reason why hci_notifier must be an atomic notifier? > > > > > > > > > > (CC'ing Alan Stern just in case, apparently hci_notifier became atomic > > > > > when notifier chains were classified into atomic / blocking) > > > > > > > > I don't remember exactly why this particular choice was made. Perhaps we > > > > found that the notifier callout routines didn't use any blocking > > > > primitives (we may have been mistaken about this -- there was a lot of > > > > code to check) and so therefore the choice didn't matter. In that case we > > > > probably just decided to make it an atomic notifier to keep things simple. > > > > > > > > As you found, changing it to a blocking notifier is very easy. Provided > > > > all the callers are non-atomic it should work just fine. > > > > > > Okay, I'll go ahead and try the patch, then, and report back. > > > > You'd still get the BUG message. To fully resolve the problem, we need > > to make the hci_sock_dev_event() notifier callout blocking (which > > happened with this patch) but also convert hci_sk_list.lock to a > > rwsem, but some users of that rwlock (other than hci_sock_dev_event) > > are atomic. > > > > However, please do try and get back, as your testing would still be > > helpful to see whether converting hci_notifier to blocking had other > > side-effects -- if you only see the same message again and otherwise > > things seem fine, then we're good as far as at least this change was > > concerned. > > Yes, it's roughly the same trace. There are some differences, though > those are likely due to me finding a new way to trigger the issue. (My > laptop has a button to turn the WiFi/Bluetooth on and off. Hitting > that and causing a disconnect of the internal Bluetooth connector > triggers the same issue without going through a suspend/resume cycle.)
Hi Ray,
This issue has actually been resolved, see the patch at: http://lkml.org/lkml/2007/5/16/149
[ We've slightly altered the locking scheme, but it's also good to know that converting hci_notifier to a blocking notifier doesn't cause any troubles either. If this is fine with other drivers too, this could actually be a separate patch. ]
I'll also soon send that patch to Andrew, will Cc you too.
Thanks, Satyam - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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