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/chan_kern.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/chan_kern.c')
-rw-r--r-- | arch/um/drivers/chan_kern.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/um/drivers/chan_kern.c b/arch/um/drivers/chan_kern.c index c09dbdf..db3082b 100644 --- a/arch/um/drivers/chan_kern.c +++ b/arch/um/drivers/chan_kern.c @@ -291,6 +291,9 @@ int write_chan(struct list_head *chans, const char *buf, int len, struct chan *chan = NULL; int n, ret = 0; + if (len == 0) + return 0; + list_for_each(ele, chans) { chan = list_entry(ele, struct chan, list); if (!chan->output || (chan->ops->write == NULL)) |