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tty: tty_buffer: invert conditions in __tty_buffer_request_room()

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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>
This commit is contained in:
Jiri Slaby (SUSE)
2023-08-16 12:55:30 +02:00
committed by Greg Kroah-Hartman
parent 035197c908
commit ebee41c849
1 changed files with 22 additions and 22 deletions
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44
drivers/tty/tty_buffer.c
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@@ -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;
}