Messages in this thread | | | Date | Wed, 15 Nov 2023 16:39:21 +0000 | Subject | Re: [PATCH v3 1/4] coresight: ultrasoc-smb: Fix sleep while close preempt in enable_smb | From | James Clark <> |
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On 14/11/2023 13:33, Junhao He wrote: > When we to enable the SMB by perf, the perf sched will call perf_ctx_lock() > to close system preempt in event_function_call(). But SMB::enable_smb() use > mutex to lock the critical section, which may sleep. > > BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580 > in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 153023, name: perf > preempt_count: 2, expected: 0 > RCU nest depth: 0, expected: 0 > INFO: lockdep is turned off. > irq event stamp: 0 > hardirqs last enabled at (0): [<0000000000000000>] 0x0 > hardirqs last disabled at (0): [<ffffa2983f5c5f40>] copy_process+0xae8/0x2b48 > softirqs last enabled at (0): [<ffffa2983f5c5f40>] copy_process+0xae8/0x2b48 > softirqs last disabled at (0): [<0000000000000000>] 0x0 > CPU: 2 PID: 153023 Comm: perf Kdump: loaded Tainted: G W O 6.5.0-rc4+ #1 > > Call trace: > ... > __mutex_lock+0xbc/0xa70 > mutex_lock_nested+0x34/0x48 > smb_update_buffer+0x58/0x360 [ultrasoc_smb] > etm_event_stop+0x204/0x2d8 [coresight] > etm_event_del+0x1c/0x30 [coresight] > event_sched_out+0x17c/0x3b8 > group_sched_out.part.0+0x5c/0x208 > __perf_event_disable+0x15c/0x210 > event_function+0xe0/0x230 > remote_function+0xb4/0xe8 > generic_exec_single+0x160/0x268 > smp_call_function_single+0x20c/0x2a0 > event_function_call+0x20c/0x220 > _perf_event_disable+0x5c/0x90 > perf_event_for_each_child+0x58/0xc0 > _perf_ioctl+0x34c/0x1250 > perf_ioctl+0x64/0x98 > ... > > Use spinlock to replace mutex to control driver data access to one at a > time. The function copy_to_user() may sleep, it cannot be in a spinlock > context, so we can't simply replace it in smb_read(). But we can ensure > that only one user gets the SMB device fd by smb_open(), so remove the > locks from smb_read() and buffer synchronization is guaranteed by the user. > > Fixes: 06f5c2926aaa ("drivers/coresight: Add UltraSoc System Memory Buffer driver") > Signed-off-by: Junhao He <hejunhao3@huawei.com>
Reviewed-by: James Clark <james.clark@arm.com>
> --- > drivers/hwtracing/coresight/ultrasoc-smb.c | 35 +++++++++------------- > drivers/hwtracing/coresight/ultrasoc-smb.h | 6 ++-- > 2 files changed, 17 insertions(+), 24 deletions(-) > > diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.c b/drivers/hwtracing/coresight/ultrasoc-smb.c > index e9a32a97fbee..0a0fe9fcc57f 100644 > --- a/drivers/hwtracing/coresight/ultrasoc-smb.c > +++ b/drivers/hwtracing/coresight/ultrasoc-smb.c > @@ -99,7 +99,7 @@ static int smb_open(struct inode *inode, struct file *file) > struct smb_drv_data, miscdev); > int ret = 0; > > - mutex_lock(&drvdata->mutex); > + spin_lock(&drvdata->spinlock); > > if (drvdata->reading) { > ret = -EBUSY; > @@ -115,7 +115,7 @@ static int smb_open(struct inode *inode, struct file *file) > > drvdata->reading = true; > out: > - mutex_unlock(&drvdata->mutex); > + spin_unlock(&drvdata->spinlock); > > return ret; > } > @@ -132,10 +132,8 @@ static ssize_t smb_read(struct file *file, char __user *data, size_t len, > if (!len) > return 0; > > - mutex_lock(&drvdata->mutex); > - > if (!sdb->data_size) > - goto out; > + return 0; > > to_copy = min(sdb->data_size, len); > > @@ -145,20 +143,15 @@ static ssize_t smb_read(struct file *file, char __user *data, size_t len, > > if (copy_to_user(data, sdb->buf_base + sdb->buf_rdptr, to_copy)) { > dev_dbg(dev, "Failed to copy data to user\n"); > - to_copy = -EFAULT; > - goto out; > + return -EFAULT; > } > > *ppos += to_copy; > - > smb_update_read_ptr(drvdata, to_copy); > - > - dev_dbg(dev, "%zu bytes copied\n", to_copy); > -out: > if (!sdb->data_size) > smb_reset_buffer(drvdata); > - mutex_unlock(&drvdata->mutex); > > + dev_dbg(dev, "%zu bytes copied\n", to_copy); > return to_copy; > } > > @@ -167,9 +160,9 @@ static int smb_release(struct inode *inode, struct file *file) > struct smb_drv_data *drvdata = container_of(file->private_data, > struct smb_drv_data, miscdev); > > - mutex_lock(&drvdata->mutex); > + spin_lock(&drvdata->spinlock); > drvdata->reading = false; > - mutex_unlock(&drvdata->mutex); > + spin_unlock(&drvdata->spinlock); > > return 0; > } > @@ -262,7 +255,7 @@ static int smb_enable(struct coresight_device *csdev, enum cs_mode mode, > struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent); > int ret = 0; > > - mutex_lock(&drvdata->mutex); > + spin_lock(&drvdata->spinlock); > > /* Do nothing, the trace data is reading by other interface now */ > if (drvdata->reading) { > @@ -294,7 +287,7 @@ static int smb_enable(struct coresight_device *csdev, enum cs_mode mode, > > dev_dbg(&csdev->dev, "Ultrasoc SMB enabled\n"); > out: > - mutex_unlock(&drvdata->mutex); > + spin_unlock(&drvdata->spinlock); > > return ret; > } > @@ -304,7 +297,7 @@ static int smb_disable(struct coresight_device *csdev) > struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent); > int ret = 0; > > - mutex_lock(&drvdata->mutex); > + spin_lock(&drvdata->spinlock); > > if (drvdata->reading) { > ret = -EBUSY; > @@ -327,7 +320,7 @@ static int smb_disable(struct coresight_device *csdev) > > dev_dbg(&csdev->dev, "Ultrasoc SMB disabled\n"); > out: > - mutex_unlock(&drvdata->mutex); > + spin_unlock(&drvdata->spinlock); > > return ret; > } > @@ -408,7 +401,7 @@ static unsigned long smb_update_buffer(struct coresight_device *csdev, > if (!buf) > return 0; > > - mutex_lock(&drvdata->mutex); > + spin_lock(&drvdata->spinlock); > > /* Don't do anything if another tracer is using this sink. */ > if (atomic_read(&csdev->refcnt) != 1) > @@ -432,7 +425,7 @@ static unsigned long smb_update_buffer(struct coresight_device *csdev, > if (!buf->snapshot && lost) > perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED); > out: > - mutex_unlock(&drvdata->mutex); > + spin_unlock(&drvdata->spinlock); > > return data_size; > } > @@ -590,7 +583,7 @@ static int smb_probe(struct platform_device *pdev) > return ret; > } > > - mutex_init(&drvdata->mutex); > + spin_lock_init(&drvdata->spinlock); > drvdata->pid = -1; > > ret = smb_register_sink(pdev, drvdata); > diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.h b/drivers/hwtracing/coresight/ultrasoc-smb.h > index d2e14e8d2c8a..82a44c14a882 100644 > --- a/drivers/hwtracing/coresight/ultrasoc-smb.h > +++ b/drivers/hwtracing/coresight/ultrasoc-smb.h > @@ -8,7 +8,7 @@ > #define _ULTRASOC_SMB_H > > #include <linux/miscdevice.h> > -#include <linux/mutex.h> > +#include <linux/spinlock.h> > > /* Offset of SMB global registers */ > #define SMB_GLB_CFG_REG 0x00 > @@ -105,7 +105,7 @@ struct smb_data_buffer { > * @csdev: Component vitals needed by the framework. > * @sdb: Data buffer for SMB. > * @miscdev: Specifics to handle "/dev/xyz.smb" entry. > - * @mutex: Control data access to one at a time. > + * @spinlock: Control data access to one at a time. > * @reading: Synchronise user space access to SMB buffer. > * @pid: Process ID of the process being monitored by the > * session that is using this component. > @@ -116,7 +116,7 @@ struct smb_drv_data { > struct coresight_device *csdev; > struct smb_data_buffer sdb; > struct miscdevice miscdev; > - struct mutex mutex; > + spinlock_t spinlock; > bool reading; > pid_t pid; > enum cs_mode mode;
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