[PATCH v2 1/5] tracing/user_events: Store register flags on events

Beau Belgrave
2023-06-05T23:39:09Z

Currently we don't have any available flags for user processes to use to
indicate options for user_events. We will soon have a flag to indicate
the event should or should not auto-delete once it's not being used by
anyone.

Add a reg_flags field to user_events and parameters to existing
functions to allow for this in future patches.

Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
---
kernel/trace/trace_events_user.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
index b1ecd7677642..34aa0a5d8e2a 100644
--- a/kernel/trace/trace_events_user.c
+++ b/kernel/trace/trace_events_user.c
@@ -87,6 +87,7 @@ struct user_event {
struct list_head validators;
refcount_t refcnt;
int min_size;
+ int reg_flags;
char status;
};

@@ -163,7 +164,7 @@ typedef void (*user_event_func_t) (struct user_event *user, struct iov_iter *i,

static int user_event_parse(struct user_event_group *group, char *name,
char *args, char *flags,
- struct user_event **newuser);
+ struct user_event **newuser, int reg_flags);

static struct user_event_mm *user_event_mm_get(struct user_event_mm *mm);
static struct user_event_mm *user_event_mm_get_all(struct user_event *user);
@@ -809,7 +810,8 @@ static struct list_head *user_event_get_fields(struct trace_event_call *call)
* Upon success user_event has its ref count increased by 1.
*/
static int user_event_parse_cmd(struct user_event_group *group,
- char *raw_command, struct user_event **newuser)
+ char *raw_command, struct user_event **newuser,
+ int reg_flags)
{
char *name = raw_command;
char *args = strpbrk(name, " ");
@@ -823,7 +825,7 @@ static int user_event_parse_cmd(struct user_event_group *group,
if (flags)
*flags++ = '\0';

- return user_event_parse(group, name, args, flags, newuser);
+ return user_event_parse(group, name, args, flags, newuser, reg_flags);
}

static int user_field_array_size(const char *type)
@@ -1587,7 +1589,7 @@ static int user_event_create(const char *raw_command)

mutex_lock(&group->reg_mutex);

- ret = user_event_parse_cmd(group, name, &user);
+ ret = user_event_parse_cmd(group, name, &user, 0);

if (!ret)
refcount_dec(&user->refcnt);
@@ -1748,7 +1750,7 @@ static int user_event_trace_register(struct user_event *user)
*/
static int user_event_parse(struct user_event_group *group, char *name,
char *args, char *flags,
- struct user_event **newuser)
+ struct user_event **newuser, int reg_flags)
{
int ret;
u32 key;
@@ -1819,6 +1821,8 @@ static int user_event_parse(struct user_event_group *group, char *name,
if (ret)
goto put_user_lock;

+ user->reg_flags = reg_flags;
+
/* Ensure we track self ref and caller ref (2) */
refcount_set(&user->refcnt, 2);

@@ -2117,7 +2121,7 @@ static long user_events_ioctl_reg(struct user_event_file_info *info,
return ret;
}

- ret = user_event_parse_cmd(info->group, name, &user);
+ ret = user_event_parse_cmd(info->group, name, &user, reg.flags);

if (ret) {
kfree(name);
--
2.25.1