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authorMatthew Wilcox (Oracle) <willy@infradead.org>2023-10-20 04:35:45 +0100
committerSteven Rostedt (Google) <rostedt@goodmis.org>2023-10-20 12:16:10 -0400
commitd0ed46b60396cfa7e0056f55e1ce0b43c7db57b6 (patch)
tree5665eb52c4a46446cc2aa24e01004a1db09d5c2b /lib
parent64bf2f685c795e75dd855761c75a193ee5998731 (diff)
tracing: Move readpos from seq_buf to trace_seq
To make seq_buf more lightweight as a string buf, move the readpos member from seq_buf to its container, trace_seq. That puts the responsibility of maintaining the readpos entirely in the tracing code. If some future users want to package up the readpos with a seq_buf, we can define a new struct then. Link: https://lore.kernel.org/linux-trace-kernel/20231020033545.2587554-2-willy@infradead.org Cc: Kees Cook <keescook@chromium.org> Cc: Justin Stitt <justinstitt@google.com> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Petr Mladek <pmladek@suse.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/seq_buf.c22
1 files changed, 10 insertions, 12 deletions
diff --git a/lib/seq_buf.c b/lib/seq_buf.c
index 45c450f423fa..b7477aefff53 100644
--- a/lib/seq_buf.c
+++ b/lib/seq_buf.c
@@ -324,23 +324,24 @@ int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
* seq_buf_to_user - copy the sequence buffer to user space
* @s: seq_buf descriptor
* @ubuf: The userspace memory location to copy to
+ * @start: The first byte in the buffer to copy
* @cnt: The amount to copy
*
* Copies the sequence buffer into the userspace memory pointed to
- * by @ubuf. It starts from the last read position (@s->readpos)
- * and writes up to @cnt characters or till it reaches the end of
- * the content in the buffer (@s->len), which ever comes first.
+ * by @ubuf. It starts from @start and writes up to @cnt characters
+ * or until it reaches the end of the content in the buffer (@s->len),
+ * whichever comes first.
*
* On success, it returns a positive number of the number of bytes
* it copied.
*
* On failure it returns -EBUSY if all of the content in the
* sequence has been already read, which includes nothing in the
- * sequence (@s->len == @s->readpos).
+ * sequence (@s->len == @start).
*
* Returns -EFAULT if the copy to userspace fails.
*/
-int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
+int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, size_t start, int cnt)
{
int len;
int ret;
@@ -350,20 +351,17 @@ int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
len = seq_buf_used(s);
- if (len <= s->readpos)
+ if (len <= start)
return -EBUSY;
- len -= s->readpos;
+ len -= start;
if (cnt > len)
cnt = len;
- ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
+ ret = copy_to_user(ubuf, s->buffer + start, cnt);
if (ret == cnt)
return -EFAULT;
- cnt -= ret;
-
- s->readpos += cnt;
- return cnt;
+ return cnt - ret;
}
/**