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From: Oliver Neukum <oliver@neukum.org>
To: Matthew Garrett <mjg59@srcf.ucam.org>
Subject: Re: [REGRESSION] "USB: use kfifo to buffer usb-generic serial writes" causes gobi_loader to hang
Date: Sun, 17 Jan 2010 10:14:44 +0100
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Am Sonntag, 17. Januar 2010 03:55:35 schrieb Matthew Garrett:
> gobi_loader writes firmware to gobi USB devices (qcserial) via the USB 
> serial layer by writing it a megabyte at a time (matching the Windows 
> driver behaviour). Commit 8e8dce065088833fc418bfa5fbf035cb0726c04c 
> breaks it - strace shows the write simply hanging. ssyrq-t says the 
> backtrace is:
> 
> Jan 17 15:37:37 localhost kernel: Call Trace:
> Jan 17 15:37:37 localhost kernel: [<ffffffff8128986c>] n_tty_write+0x2da/0x351
> Jan 17 15:37:37 localhost kernel: [<ffffffff810464b4>] ? default_wake_function+0x0/0x14
> Jan 17 15:37:37 localhost kernel: [<ffffffff81286969>] tty_write+0x19d/0x245
> Jan 17 15:37:37 localhost kernel: [<ffffffff81289592>] ? n_tty_write+0x0/0x351
> Jan 17 15:37:37 localhost kernel: [<ffffffff81103e44>] vfs_write+0xae/0x10b
> Jan 17 15:37:37 localhost kernel: [<ffffffff81103f61>] sys_write+0x4a/0x6e
> Jan 17 15:37:37 localhost kernel: [<ffffffff81009e45>] tracesys+0xd9/0xde

Hi,

please load usbserial with debug=1 and post the output of just before the hang.

	Regards
		Oliver