From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: Re: [PATCH v2 0/5] serial: Finish sysrq on qcom_geni; fix sysrq vs. lockdep on 8250 Date: Fri, 9 Nov 2018 09:07:45 -0800 Message-ID: <20181109170745.GC14151@kroah.com> References: <20181030221107.79758-1-dianders@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20181030221107.79758-1-dianders@chromium.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Douglas Anderson Cc: dan.carpenter@oracle.com, vigneshr@ti.com, linux-aspeed@lists.ozlabs.org, andrew@aj.id.au, linux-arm-msm@vger.kernel.org, tony@atomide.com, joel@jms.id.au, linux-serial@vger.kernel.org, Jiri Slaby , andriy.shevchenko@linux.intel.com, linux-arm-kernel@lists.infradead.org, jk@ozlabs.org List-Id: linux-arm-msm@vger.kernel.org On Tue, Oct 30, 2018 at 03:11:02PM -0700, Douglas Anderson wrote: > I started out this series trying to make sysrq work over the serial > console on qcom_geni_serial, then fell into a rat's nest. > > To solve the deadlock I faced when enabling sysrq I tried to borrow > code from '8250_port.c' which avoided grabbing the port lock in > console_write(). ...but since these days I try to run with lockdep on > all the time, I found it caused an annoying lockdep splat (which I > also reproduced on my rk3399 board). ...so I instead changed my > qcom_geni_serial solution to borrow code from 'msm_serial.c' > > I wasn't super happy with the solution in 'msm_serial.c' though. I > don't like releasing the spinlock there. Not only is it ugly but it > means we are unlocking / re-locking _all the time_ even though sysrq > characters are rare. ...so I came up with what I think is a better > solution and then implemented it for qcom_geni_serial. > > Since I had a good way to test 8250-based UARTs, I also fixed that > driver to use my new method. When doing so, I ran into a missing > include in serial_core.h. NOTE: I didn't have a way to test > msm_serial.c at all, so I didn't switch that (or all other serial > drivers for that matter) to the new method. > > NOTE: from a serial point of view v2 is the same as v1 but I've > removed the extra kgdb-related patches and made it obvious that this > is really for all sysrq, not just kgdb. I've also generally tried to > curate the CCs more properly. Looks good, thanks for cleaning this up. All now queued up. greg k-h