diff options
author | Jeff Dike <jdike@addtoit.com> | 2007-10-16 08:26:42 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-16 16:43:04 (GMT) |
commit | c59dbcadd5d125ba40595612dc91ab18924164d3 (patch) | |
tree | a0970a23641babc6d9b54074316a6686322b69d2 /arch/um/drivers/line.c | |
parent | e99525f9706900417f37721e601d2b414d41bfee (diff) | |
download | linux-c59dbcadd5d125ba40595612dc91ab18924164d3.tar.xz |
uml: fix console writing bugs
The previous console cleanup patch switched generic_read and generic_write
from calling os_{read,write}_file to calling read and write directly. Because
the calling convention is different, they now need to get any error from errno
rather than the return value. I did this for generic_read, but forgot about
generic_write.
While chasing some output corruption, I noticed that line_write was
unnecessarily calling flush_buffer, and deleted it. I don't understand why,
but the corruption disappeared. This is unneeded because there already is a
perfectly good mechanism for finding out when the host output device has some
room to write data - there is an interrupt that comes in when writes can
happen again. line_write calling flush_buffer seemed to just be an attempt to
opportunistically get some data out to the host.
I also made write_chan short-circuit calling into the host-level code for
zero-length writes. Calling libc write with a length of zero conflated write
not being able to write anything with asking it not to write anything. Better
to just cut it off as soon as possible.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/um/drivers/line.c')
-rw-r--r-- | arch/um/drivers/line.c | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c index 3e0b68e..b4538df 100644 --- a/arch/um/drivers/line.c +++ b/arch/um/drivers/line.c @@ -216,18 +216,15 @@ int line_write(struct tty_struct *tty, const unsigned char *buf, int len) { struct line *line = tty->driver_data; unsigned long flags; - int n, err, ret = 0; + int n, ret = 0; if(tty->stopped) return 0; spin_lock_irqsave(&line->lock, flags); - if (line->head != line->tail) { + if (line->head != line->tail) ret = buffer_data(line, buf, len); - err = flush_buffer(line); - if (err <= 0 && (err != -EAGAIN || !ret)) - ret = err; - } else { + else { n = write_chan(&line->chan_list, buf, len, line->driver->write_irq); if (n < 0) { |