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authorJiri Slaby (SUSE) <jirislaby@kernel.org>2023-08-16 12:55:30 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2023-08-22 14:58:16 +0200
commitebee41c8490aeb3ef2e7d25f5e97ce45c996da4d (patch)
tree18728900e1ad44334b57aa7d0e087b2b981da5c4 /drivers/tty
parent035197c908b57804b9407cf119d2c2fe5934ee00 (diff)
tty: tty_buffer: invert conditions in __tty_buffer_request_room()
We are used to handle "bad" states in the 'if's in the kernel. Refactor (invert the two conditions in) __tty_buffer_request_room(), so that the code returns from the fast paths immediately instead of postponing to the heavy end of the function. Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org> Link: https://lore.kernel.org/r/20230816105530.3335-11-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/tty_buffer.c44
1 files changed, 22 insertions, 22 deletions
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 44c0adaec850..5f6d0cf67571 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -266,28 +266,28 @@ static int __tty_buffer_request_room(struct tty_port *port, size_t size,
size_t left = (b->flags ? 1 : 2) * b->size - b->used;
bool change = !b->flags && flags;
- if (change || left < size) {
- /* This is the slow path - looking for new buffers to use */
- n = tty_buffer_alloc(port, size);
- if (n != NULL) {
- n->flags = flags;
- buf->tail = n;
- /*
- * Paired w/ acquire in flush_to_ldisc() and lookahead_bufs()
- * ensures they see all buffer data.
- */
- smp_store_release(&b->commit, b->used);
- /*
- * Paired w/ acquire in flush_to_ldisc() and lookahead_bufs()
- * ensures the latest commit value can be read before the head
- * is advanced to the next buffer.
- */
- smp_store_release(&b->next, n);
- } else if (change)
- size = 0;
- else
- size = left;
- }
+ if (!change && left >= size)
+ return size;
+
+ /* This is the slow path - looking for new buffers to use */
+ n = tty_buffer_alloc(port, size);
+ if (n == NULL)
+ return change ? 0 : left;
+
+ n->flags = flags;
+ buf->tail = n;
+ /*
+ * Paired w/ acquire in flush_to_ldisc() and lookahead_bufs()
+ * ensures they see all buffer data.
+ */
+ smp_store_release(&b->commit, b->used);
+ /*
+ * Paired w/ acquire in flush_to_ldisc() and lookahead_bufs()
+ * ensures the latest commit value can be read before the head
+ * is advanced to the next buffer.
+ */
+ smp_store_release(&b->next, n);
+
return size;
}