From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kumar Sanghvi Subject: Re: [PATCH] RDMA/cxgb4: Unblock reads on comp_channel Date: Fri, 21 Oct 2011 13:02:58 +0530 Message-ID: <20111021073254.GA23539@kumars-PC.asicdesigners.com> References: <1318494090-9996-1-git-send-email-kumaras@chelsio.com> <4E970E02.2090207@opengridcomputing.com> <88B766C272F2C64B944B21AD078333151BEE2E947E@EXMAIL.ad.emulex.com> <4EA04A95.9010908@opengridcomputing.com> <88B766C272F2C64B944B21AD078333151BEE2E9521@EXMAIL.ad.emulex.com> <4EA05AA0.4030201@opengridcomputing.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4EA05AA0.4030201-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Steve Wise Cc: Parav.Pandit-iH1Dq9VlAzfQT0dZR+AlfA@public.gmane.org, roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, divy-ut6Up61K2wZBDgjK7y7TUQ@public.gmane.org List-Id: linux-rdma@vger.kernel.org On Thu, Oct 20, 2011 at 12:30:08 -0500, Steve Wise wrote: > On 10/20/2011 12:25 PM, Parav.Pandit-iH1Dq9VlAzfQT0dZR+AlfA@public.gmane.org wrote: > >You are right, cq_lock will result into dead lock. > >Should there be a additional compl_handler spin_lock? > >I was measuring performance impact for adding it, and, irq_save() and irq_restore() variant showed additional 200 cycles, which I believe should be o.k.? > > > >Parav > > > > Yea, I think adding a comp_handler spin lock would do the trick. I'll let Kumar come up with this change. I will cook up a patch and post soon. Thanks, Kumar. > > > > >-----Original Message----- > >From: Steve Wise [mailto:swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org] > >Sent: Thursday, October 20, 2011 9:52 PM > >To: Roland Dreier > >Cc: Pandit, Parav; kumaras-ut6Up61K2wZBDgjK7y7TUQ@public.gmane.org; linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; divy-ut6Up61K2wZBDgjK7y7TUQ@public.gmane.org > >Subject: Re: [PATCH] RDMA/cxgb4: Unblock reads on comp_channel > > > >On 10/20/2011 11:06 AM, Roland Dreier wrote: > >>On Thu, Oct 20, 2011 at 2:11 AM, wrote: > >>>http://lxr.linux.no/#linux+v3.0.4/Documentation/infiniband/core_locking.txt > >>> > >>>Line no 66 to 97 states that - at a given point of time, there should be only one callback per CQ should be active. > >>>Is this ensured? > >>> > >>>compl_handler() is invoked from multiple places flush_qp() and post_qp_event() to my mind. > >>Yes, does look like an issue with this patch :( > >> > >And I think this bug exists in the T3 driver too. > > > -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html