On 02/03/2017 05:19 PM, Christoph Hellwig wrote:
On Fri, Feb 03, 2017 at 02:38:35PM +0100, Hannes Reinecke wrote:
On 02/03/2017 02:31 PM, Christoph Hellwig wrote:
- if (sg_res_in_use(sfp)) {
+ mutex_lock(&sfp->f_mutex);
+ if (sfp->res_in_use) {
+ mutex_unlock(&sfp->f_mutex);
sg_remove_request(sfp, srp);
return -EBUSY; /* reserve buffer already being used */
}
+ mutex_unlock(&sfp->f_mutex);
Holding a mutex over a the check of a single scalar doesn't make sense.
It's adds a synchronisation point, doesn't it?
It does, but it doesn't actually protect anything..
But all the other mutex_{un,}locks() do (for instance guarding
sg_build_indirect()) and this one provides a synchronization point.
Sorry but I really don't get your point here.
The sole purpose is to guard the reserved list from being altered while
blk_rq_map_* or similar functions are in progess (that's what the
syzcaller reproducer was doing).
Byte,
Johannes
