Re: 2.6.7-mm7

[Andrew Morton]

Jesse Stockall <stockall@xxxxxxxx> wrote:
>
> On Fri, 2004-07-09 at 14:54, Andrew Morton wrote:
>                        down_write_trylock(&usb_all_devices_rwsem));
>  > 
>  > That's a bit unusual.  Could you (or Alan) please explain the reason for
>  > this a little more?
> 
>  I believe you want this thread
> 
>  http://marc.theaimsgroup.com/?l=linux-usb-devel&m=108923404032264&w=2

Oh, OK.  Recursively taking an rwsem for reading is certainly deadlocky. 
The main reason for not supporting this is that heavy down_read() traffic
can trivially livelock down_write() waiters.  Alan's patch will introduce
that shortcoming.

Really, it would be better to get the locking sorted out.
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