> -----Original Message----- > From: Jason Gunthorpe [mailto:[email protected]] > Sent: Tuesday, October 27, 2015 2:17 PM > To: Weiny, Ira > Cc: Saurabh Sengar; [email protected]; Hefty, Sean; > [email protected]; [email protected]; Wan, Kaike; linux- > [email protected]; [email protected] > Subject: Re: [PATCH] IB/sa: replace GFP_KERNEL with GFP_ATOMIC > > On Tue, Oct 27, 2015 at 02:12:36PM -0400, ira.weiny wrote: > > On Tue, Oct 27, 2015 at 09:17:40PM +0530, Saurabh Sengar wrote: > > > replace GFP_KERNEL with GFP_ATOMIC, as code while holding a spinlock > > > should be atomic GFP_KERNEL may sleep and can cause deadlock, where > > > as GFP_ATOMIC may fail but certainly avoids deadlock > > > > Great catch. Thanks! > > > > However, gfp_t is passed to send_mad and we should pass that down and > use it. > > > spin_lock_irqsave(&ib_nl_request_lock, flags); > > - ret = ib_nl_send_msg(query); > > + ret = ib_nl_send_msg(query, gfp_mask); > > A spin lock is guarenteed held around ib_nl_send_msg, so it's allocations > have to be atomic, can't use gfp_mask here.. > > I do wonder if it is a good idea to call ib_nl_send_msg with a spinlock held > though.. Would be nice to see that go away.
We have to hold the lock to protect against a race condition that a quick response will try to free the request from the ib_nl_request_list before we even put it on the list. > > Jason -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
