Messages in this thread | | | Date | Wed, 30 Sep 2009 16:50:26 +0200 | From | Tilman Schmidt <> | Subject | N_PPP_SYNC ldisc BUG: sleeping function called from invalid context |
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While testing pppd with capiplugin on kernel 2.6.31 (plus my CAPI and Gigaset patches) I came across this BUG message. (Please ignore the Tainted flag, it's from the Nvidia driver and doesn't influence what's following.)
BUG: sleeping function called from invalid context at kernel/mutex.c:280 in_atomic(): 1, irqs_disabled(): 1, pid: 10, name: events/0 INFO: lockdep is turned off. irq event stamp: 2034 hardirqs last enabled at (2033): [<c0347b07>] _spin_unlock_irqrestore+0x3c/0x6c hardirqs last disabled at (2034): [<c03475d0>] _spin_lock_irq+0x11/0x3f softirqs last enabled at (2008): [<c012f598>] __do_softirq+0x114/0x11c softirqs last disabled at (1971): [<c010593a>] do_softirq+0x69/0xc7 Pid: 10, comm: events/0 Tainted: P 2.6.31-vanilla #1 Call Trace: [<c0124a3c>] __might_sleep+0x10e/0x116 [<c0346bdd>] mutex_lock_nested+0x18/0x31 [<c026d39b>] tty_unthrottle+0x10/0x38 [<f8dcc31f>] ppp_sync_receive+0x168/0x170 [ppp_synctty] [<f8fbb9ce>] handle_minor_recv+0x187/0x1cd [capi] [<f8fbc19b>] capi_recv_message+0x1d9/0x24e [capi] [<fa5be461>] recv_handler+0x56/0x6f [kernelcapi] [<c0138cba>] worker_thread+0x14a/0x21d [<c0138c9e>] ? worker_thread+0x12e/0x21d [<fa5be40b>] ? recv_handler+0x0/0x6f [kernelcapi] [<c013b375>] ? autoremove_wake_function+0x0/0x30 [<c013b201>] kthread+0x64/0x69 [<c0138b70>] ? worker_thread+0x0/0x21d [<c013b19d>] ? kthread+0x0/0x69 [<c0103f33>] kernel_thread_helper+0x7/0x10
Turns out the ppp_sync_receive() function (drivers/net/ppp_synctty.c line 385ff.) has a comment in front stating:
/* * This can now be called from hard interrupt level as well * as soft interrupt level or mainline. */
but calls tty_unthrottle() which in turn calls mutex_lock() which of course can sleep.
That tty_unthrottle() call was already removed once by
commit a6540f731d506d9e82444cf0020e716613d4c46c Author: Alan Cox <alan@linux.intel.com> Date: Mon Jun 22 18:42:29 2009 +0100
ppp: Fix throttling bugs
but re-added by
commit 4a21b8cb3550f19f838f7c48345fbbf6a0e8536b Author: Linus Torvalds <torvalds@linux-foundation.org> Date: Thu Jul 16 09:14:23 2009 -0700
Revert "ppp: Fix throttling bugs"
This reverts commit a6540f731d506d9e82444cf0020e716613d4c46c, as requested by Alan:
"... as it was wrong, the pty code is now fixed and the fact this isn't reverted is breaking pptp setups."
Opinions?
Thanks, Tilman
- -- Tilman Schmidt E-Mail: tilman@imap.cc Bonn, Germany Diese Nachricht besteht zu 100% aus wiederverwerteten Bits. Ungeöffnet mindestens haltbar bis: (siehe Rückseite) -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.4 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org
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