Messages in this thread | | | Date | Mon, 7 May 2007 05:26:05 +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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(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.
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