From mboxrd@z Thu Jan 1 00:00:00 1970 From: mathieu.poirier@linaro.org (Mathieu Poirier) Date: Tue, 31 Jul 2018 11:07:31 -0600 Subject: [PATCH v3 02/13] coresight: etb10: Fix handling of perf mode In-Reply-To: <1532609691-16863-3-git-send-email-suzuki.poulose@arm.com> References: <1532609691-16863-1-git-send-email-suzuki.poulose@arm.com> <1532609691-16863-3-git-send-email-suzuki.poulose@arm.com> Message-ID: <20180731170731.GA11692@xps15> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hello, On Thu, Jul 26, 2018 at 01:54:40PM +0100, Suzuki K Poulose wrote: > If the ETB is already enabled in sysfs mode, the ETB reports > success even if a perf mode is requested. Fix this by checking > the requested mode. > > Cc: Mathieu Poirier > Signed-off-by: Suzuki K Poulose > --- > drivers/hwtracing/coresight/coresight-etb10.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c > index 306119e..e5808fd 100644 > --- a/drivers/hwtracing/coresight/coresight-etb10.c > +++ b/drivers/hwtracing/coresight/coresight-etb10.c > @@ -148,8 +148,12 @@ static int etb_enable(struct coresight_device *csdev, u32 mode) > return -EBUSY; > > /* Nothing to do, the tracer is already enabled. */ > - if (val == CS_MODE_SYSFS) > - goto out; > + if (val == CS_MODE_SYSFS) { > + if (mode == CS_MODE_SYSFS) > + goto out; > + else > + return -EBUSY; > + } How about: if (val == CS_MODE_PERF) return -EBUSY; + /* Don't let perf disturb sysFS sessions */ + if (val == CS_MODE_SYSFS && mode = CS_MODE_PERF) + return -EBUSY; + /* Nothing to do, the tracer is already enabled. */ if (val == CS_MODE_SYSFS) goto out; I just find it more readable that way. Thanks, Mathieu > > spin_lock_irqsave(&drvdata->spinlock, flags); > etb_enable_hw(drvdata); > -- > 2.7.4 >