From: Junhao He Date: Tue, 14 Nov 2023 13:33:43 +0000 (+0800) Subject: coresight: ultrasoc-smb: Fix sleep while close preempt in enable_smb X-Git-Tag: v6.6.7~53 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ace850bd8600328f8f56e41db88d7b232ab939d4;p=platform%2Fkernel%2Flinux-starfive.git coresight: ultrasoc-smb: Fix sleep while close preempt in enable_smb [ Upstream commit b8411287aef4a994eff0c68f5597910c4194dfe3 ] 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): [] copy_process+0xae8/0x2b48 softirqs last enabled at (0): [] 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 Reviewed-by: James Clark Signed-off-by: Suzuki K Poulose Link: https://lore.kernel.org/r/20231114133346.30489-2-hejunhao3@huawei.com Signed-off-by: Sasha Levin --- diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.c b/drivers/hwtracing/coresight/ultrasoc-smb.c index e9a32a9..0a0fe9f 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 d2e14e8..82a44c1 100644 --- a/drivers/hwtracing/coresight/ultrasoc-smb.h +++ b/drivers/hwtracing/coresight/ultrasoc-smb.h @@ -8,7 +8,7 @@ #define _ULTRASOC_SMB_H #include -#include +#include /* 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;