Re: [PATCH] tty: hold lock across tty buffer finding and bufferfilling

[Alan Cox]

On Thu, 15 Mar 2012 10:14:07 +0000
"Du, Alek" <alek.du@xxxxxxxxx> wrote:

> Alan,
> 
> I agree with you for the case of multiple writers to the tty buffer.
> 
> But there is another case that cause kernel hang: driver is writing data to tty, while app shutdown the port or flush through IOCTL. The buf.tail is set to NULL, here is the log:
> 
> 
> <1>[ 4713.451954] BUG: unable to handle kernel NULL pointer dereference at
> 00000004
> <1>[ 4713.452424] IP: [<c14ff59c>] tty_insert_flip_string_fixed_flag+0x4c/0x90


Ouch.. yes that makes sense.

Alan
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