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This is similar to the regular Tracefs interface. Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort diff --git a/include/linux/trace_remote.h b/include/linux/trace_remote.h index bd327a8184a0..7fb5271a8c30 100644 --- a/include/linux/trace_remote.h +++ b/include/linux/trace_remote.h @@ -18,6 +18,8 @@ * remote to allow writing. * @swap_reader_page: Called when Tracefs consumes a new page from a * ring-buffer. It is expected from the remote to isolate a + * @reset: Called on `echo 0 > trace`. It is expected from the + * remote to reset all ring-buffer pages. * new reader-page from the @cpu ring-buffer. */ struct trace_remote_callbacks { @@ -25,6 +27,7 @@ struct trace_remote_callbacks { void (*unload_trace_buffer)(struct trace_buffer_desc *desc, void *priv); int (*enable_tracing)(bool enable, void *priv); int (*swap_reader_page)(unsigned int cpu, void *priv); + int (*reset)(unsigned int cpu, void *priv); }; int trace_remote_register(const char *name, struct trace_remote_callbacks *cbs, void *priv); diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c index f8ab328df70a..82060bb19ba1 100644 --- a/kernel/trace/trace_remote.c +++ b/kernel/trace/trace_remote.c @@ -63,6 +63,7 @@ static int trace_remote_load(struct trace_remote *remote) rb_remote->desc = desc; rb_remote->swap_reader_page = remote->cbs->swap_reader_page; rb_remote->priv = remote->priv; + rb_remote->reset = remote->cbs->reset; remote->trace_buffer = ring_buffer_alloc_remote(rb_remote); if (!remote->trace_buffer) { remote->cbs->unload_trace_buffer(desc, remote->priv); @@ -138,6 +139,21 @@ static int trace_remote_disable_tracing(struct trace_remote *remote) return 0; } +static void trace_remote_reset(struct trace_remote *remote, int cpu) +{ + lockdep_assert_held(&remote->lock); + + if (!trace_remote_loaded(remote)) + return; + + if (cpu == RING_BUFFER_ALL_CPUS) + ring_buffer_reset(remote->trace_buffer); + else + ring_buffer_reset_cpu(remote->trace_buffer, cpu); + + trace_remote_try_unload(remote); +} + static ssize_t tracing_on_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *ppos) { @@ -414,6 +430,26 @@ static const struct file_operations trace_pipe_fops = { .release = trace_pipe_release, }; +static ssize_t trace_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *ppos) +{ + struct inode *inode = file_inode(filp); + struct trace_remote *remote = inode->i_private; + int cpu = RING_BUFFER_ALL_CPUS; + + if (inode->i_cdev) + cpu = (long)inode->i_cdev - 1; + + guard(mutex)(&remote->lock); + + trace_remote_reset(remote, cpu); + + return cnt; +} + +static const struct file_operations trace_fops = { + .write = trace_write, +}; + static int trace_remote_init_tracefs(const char *name, struct trace_remote *remote) { struct dentry *remote_d, *percpu_d, *d; @@ -452,6 +488,10 @@ static int trace_remote_init_tracefs(const char *name, struct trace_remote *remo if (!d) goto err; + d = trace_create_file("trace", TRACEFS_MODE_WRITE, remote_d, remote, &trace_fops); + if (!d) + goto err; + percpu_d = tracefs_create_dir("per_cpu", remote_d); if (!percpu_d) { pr_err("Failed to create tracefs dir "TRACEFS_DIR"%s/per_cpu/\n", name); @@ -474,6 +514,11 @@ static int trace_remote_init_tracefs(const char *name, struct trace_remote *remo &trace_pipe_fops); if (!d) goto err; + + d = trace_create_cpu_file("trace", TRACEFS_MODE_WRITE, cpu_d, remote, cpu, + &trace_fops); + if (!d) + goto err; } return 0; -- 2.53.0.rc1.225.gd81095ad13-goog