Re: [PATCH v6 07/24] tracing: Add events/ root files to trace remotes
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2025-09-09 21:51:57
Also in:
kvmarm, linux-arm-kernel, lkml
On Thu, 21 Aug 2025 09:13:55 +0100 Vincent Donnefort [off-list ref] wrote:
quoted hunk ↗ jump to hunk
diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c index 822cdd76e334..5065b162c8ef 100644 --- a/kernel/trace/trace_remote.c +++ b/kernel/trace/trace_remote.c@@ -710,10 +710,118 @@ static int remote_event_callback(const char *name, umode_t *mode, void **data, return 0; } +static ssize_t remote_events_dir_enable_write(struct file *filp, const char __user *ubuf, + size_t count, loff_t *ppos) +{ + struct trace_remote *remote = file_inode(filp)->i_private; + u8 enable; + int i, ret; + + ret = kstrtou8_from_user(ubuf, count, 10, &enable); + if (ret) + return ret; + + guard(mutex)(&remote->lock); + + for (i = 0; i < remote->nr_events; i++) { + struct remote_event *evt = &remote->events[i]; + + trace_remote_enable_event(remote, evt, enable); + } + + return count; +} + +static const struct file_operations remote_events_dir_enable_fops = { + .write = remote_events_dir_enable_write,
Hmm, why not a read as well? Or is it too difficult to figure out what is enabled and what isn't. For the main trace buffer, it's: 0 - all disabled 1 - all enabled X - some disabled some enabled
+};
+
+static ssize_t
+remote_events_dir_header_page_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+ struct trace_seq *s;
+ int ret;
+
+ s = kmalloc(sizeof(*s), GFP_KERNEL);
+ if (!s)
+ return -ENOMEM;
+
+ trace_seq_init(s);
+
+ ring_buffer_print_page_header(NULL, s);
+ ret = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, trace_seq_used(s));
+ kfree(s);
+
+ return ret;
+}
+
+static const struct file_operations remote_events_dir_header_page_fops = {
+ .read = remote_events_dir_header_page_read,
+};
+
+static ssize_t
+remote_events_dir_header_event_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+ struct trace_seq *s;
+ int ret;
+
+ s = kmalloc(sizeof(*s), GFP_KERNEL);
+ if (!s)
+ return -ENOMEM;
+
+ trace_seq_init(s);
+
+ ring_buffer_print_entry_header(s);
+ ret = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, trace_seq_used(s));
+ kfree(s);
+
+ return ret;
+}
+
+static const struct file_operations remote_events_dir_header_event_fops = {
+ .read = remote_events_dir_header_event_read,
+};
+
+static int remote_events_dir_callback(const char *name, umode_t *mode, void **data,
+ const struct file_operations **fops)
+{
+ if (!strcmp(name, "enable")) {
+ *mode = 0200;As 0200 is a bit strange. -- Steve
quoted hunk ↗ jump to hunk
+ *fops = &remote_events_dir_enable_fops; + return 1; + } + + if (!strcmp(name, "header_page")) { + *mode = TRACEFS_MODE_READ; + *fops = &remote_events_dir_header_page_fops; + return 1; + } + + if (!strcmp(name, "header_event")) { + *mode = TRACEFS_MODE_READ; + *fops = &remote_events_dir_header_event_fops; + return 1; + } + + return 0; +} + static int trace_remote_init_eventfs(const char *remote_name, struct trace_remote *remote, struct remote_event *evt) { struct eventfs_inode *eventfs = remote->eventfs; + static struct eventfs_entry dir_entries[] = { + { + .name = "enable", + .callback = remote_events_dir_callback, + }, { + .name = "header_page", + .callback = remote_events_dir_callback, + }, { + .name = "header_event", + .callback = remote_events_dir_callback, + } + }; static struct eventfs_entry entries[] = { { .name = "enable",@@ -729,7 +837,8 @@ static int trace_remote_init_eventfs(const char *remote_name, struct trace_remot bool eventfs_create = false; if (!eventfs) { - eventfs = eventfs_create_events_dir("events", remote->dentry, NULL, 0, NULL); + eventfs = eventfs_create_events_dir("events", remote->dentry, dir_entries, + ARRAY_SIZE(dir_entries), remote); if (IS_ERR(eventfs)) return PTR_ERR(eventfs);