Messages in this thread | | | From | "Paul Fulghum" <> | Subject | Re: 2.5.74 / oops with ppp_synctty and local_bh_enable | Date | Mon, 7 Jul 2003 10:47:48 -0500 |
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> I'm using the Alcatel SpeedTouch modem. It is working fine. :-) > Meanwhile, when the pppd process is killed, the following oops appears. > ... > Jul 6 15:30:04 tigre01 kernel: Badness in local_bh_enable at kernel/softirq.c:109 > Jul 6 15:30:04 tigre01 kernel: Call Trace: > Jul 6 15:30:04 tigre01 kernel: [<c0129265>] local_bh_enable+0x85/0xa0 > Jul 6 15:30:04 tigre01 kernel: [<e982fe73>] ppp_sync_push+0xd3/0x280 [ppp_synctty] > Jul 6 15:30:04 tigre01 kernel: [<e982f768>] ppp_sync_wakeup+0x28/0x60 [ppp_synctty] > Jul 6 15:30:04 tigre01 kernel: [<c0226e32>] do_tty_hangup+0x492/0x560
The problem is that do_tty_hangup() in tty_io.h calls the write wakeup callback with disabled interrupts. The notes in this function question the validity of disabling interrupts at that point. I'm not familiar enough with the locking issues for this function to comment.
At some point ppp_synctty.c was changed to use spin_lock_bh and spin_unlock_bh in the write wakeup callback. These macros complain when called with interrupts disabled.
Perhaps changing ppp_synctty.c to use spin_lock_irqsave and spin_lock_irqrestore is the best fix.
Paul Fulghum, paulkf@microgate.com Microgate Corporation, www.microgate.com
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