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Thu, 19 Dec 2024 04:24:29 -0800 (PST) MIME-Version: 1.0 References: <20241216115006.415861-1-yeoreum.yun@arm.com> <20241216115006.415861-6-yeoreum.yun@arm.com> In-Reply-To: <20241216115006.415861-6-yeoreum.yun@arm.com> From: Mike Leach Date: Thu, 19 Dec 2024 12:24:18 +0000 Message-ID: Subject: Re: [PATCH v3 5/9] coresight-etb10: change etb_drvdata spinlock's type to raw_spinlock_t To: Yeoreum Yun Cc: suzuki.poulose@arm.com, james.clark@linaro.org, alexander.shishkin@linux.intel.com, bigeasy@linutronix.de, clrkwllms@kernel.org, rostedt@goodmis.org, coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241219_042430_809927_2D6FC57D X-CRM114-Status: GOOD ( 23.93 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, 16 Dec 2024 at 11:50, Yeoreum Yun wrote: > > In coresight-etb10 drivers, etb_drvdata->spinlock can be held > during __schedule() by perf_event_task_sched_out()/in(). > > Since etb_drvdata->spinlock type is spinlock_t and > perf_event_task_sched_out()/in() is called after acquiring rq_lock, > which is raw_spinlock_t (an unsleepable lock), > this poses an issue in PREEMPT_RT kernel where spinlock_t is sleepable. > > To address this, change type etb_drvdata->spinlock in coresight-etb10 drivers, > which can be called by perf_event_task_sched_out()/in(), > from spinlock_t to raw_spinlock_t. > > Signed-off-by: Yeoreum Yun > --- > drivers/hwtracing/coresight/coresight-etb10.c | 26 +++++++++---------- > 1 file changed, 13 insertions(+), 13 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c > index aea9ac9c4bd0..7948597d483d 100644 > --- a/drivers/hwtracing/coresight/coresight-etb10.c > +++ b/drivers/hwtracing/coresight/coresight-etb10.c > @@ -84,7 +84,7 @@ struct etb_drvdata { > struct clk *atclk; > struct coresight_device *csdev; > struct miscdevice miscdev; > - spinlock_t spinlock; > + raw_spinlock_t spinlock; > local_t reading; > pid_t pid; > u8 *buf; > @@ -145,7 +145,7 @@ static int etb_enable_sysfs(struct coresight_device *csdev) > unsigned long flags; > struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); > > - spin_lock_irqsave(&drvdata->spinlock, flags); > + raw_spin_lock_irqsave(&drvdata->spinlock, flags); > > /* Don't messup with perf sessions. */ > if (coresight_get_mode(csdev) == CS_MODE_PERF) { > @@ -163,7 +163,7 @@ static int etb_enable_sysfs(struct coresight_device *csdev) > > csdev->refcnt++; > out: > - spin_unlock_irqrestore(&drvdata->spinlock, flags); > + raw_spin_unlock_irqrestore(&drvdata->spinlock, flags); > return ret; > } > > @@ -176,7 +176,7 @@ static int etb_enable_perf(struct coresight_device *csdev, void *data) > struct perf_output_handle *handle = data; > struct cs_buffers *buf = etm_perf_sink_config(handle); > > - spin_lock_irqsave(&drvdata->spinlock, flags); > + raw_spin_lock_irqsave(&drvdata->spinlock, flags); > > /* No need to continue if the component is already in used by sysFS. */ > if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) { > @@ -219,7 +219,7 @@ static int etb_enable_perf(struct coresight_device *csdev, void *data) > } > > out: > - spin_unlock_irqrestore(&drvdata->spinlock, flags); > + raw_spin_unlock_irqrestore(&drvdata->spinlock, flags); > return ret; > } > > @@ -352,11 +352,11 @@ static int etb_disable(struct coresight_device *csdev) > struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); > unsigned long flags; > > - spin_lock_irqsave(&drvdata->spinlock, flags); > + raw_spin_lock_irqsave(&drvdata->spinlock, flags); > > csdev->refcnt--; > if (csdev->refcnt) { > - spin_unlock_irqrestore(&drvdata->spinlock, flags); > + raw_spin_unlock_irqrestore(&drvdata->spinlock, flags); > return -EBUSY; > } > > @@ -366,7 +366,7 @@ static int etb_disable(struct coresight_device *csdev) > /* Dissociate from monitored process. */ > drvdata->pid = -1; > coresight_set_mode(csdev, CS_MODE_DISABLED); > - spin_unlock_irqrestore(&drvdata->spinlock, flags); > + raw_spin_unlock_irqrestore(&drvdata->spinlock, flags); > > dev_dbg(&csdev->dev, "ETB disabled\n"); > return 0; > @@ -443,7 +443,7 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev, > > capacity = drvdata->buffer_depth * ETB_FRAME_SIZE_WORDS; > > - spin_lock_irqsave(&drvdata->spinlock, flags); > + raw_spin_lock_irqsave(&drvdata->spinlock, flags); > > /* Don't do anything if another tracer is using this sink */ > if (csdev->refcnt != 1) > @@ -566,7 +566,7 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev, > __etb_enable_hw(drvdata); > CS_LOCK(drvdata->base); > out: > - spin_unlock_irqrestore(&drvdata->spinlock, flags); > + raw_spin_unlock_irqrestore(&drvdata->spinlock, flags); > > return to_read; > } > @@ -587,13 +587,13 @@ static void etb_dump(struct etb_drvdata *drvdata) > { > unsigned long flags; > > - spin_lock_irqsave(&drvdata->spinlock, flags); > + raw_spin_lock_irqsave(&drvdata->spinlock, flags); > if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) { > __etb_disable_hw(drvdata); > etb_dump_hw(drvdata); > __etb_enable_hw(drvdata); > } > - spin_unlock_irqrestore(&drvdata->spinlock, flags); > + raw_spin_unlock_irqrestore(&drvdata->spinlock, flags); > > dev_dbg(&drvdata->csdev->dev, "ETB dumped\n"); > } > @@ -746,7 +746,7 @@ static int etb_probe(struct amba_device *adev, const struct amba_id *id) > drvdata->base = base; > desc.access = CSDEV_ACCESS_IOMEM(base); > > - spin_lock_init(&drvdata->spinlock); > + raw_spin_lock_init(&drvdata->spinlock); > > drvdata->buffer_depth = etb_get_buffer_depth(drvdata); > > -- > LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7} > Reviewed-by: Mike Leach -- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK