Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=c59dbcadd5d125ba40595612dc91ab18924164d3
Commit:     c59dbcadd5d125ba40595612dc91ab18924164d3
Parent:     e99525f9706900417f37721e601d2b414d41bfee
Author:     Jeff Dike <[EMAIL PROTECTED]>
AuthorDate: Tue Oct 16 01:26:42 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue Oct 16 09:43:04 2007 -0700

    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 <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 arch/um/drivers/chan_kern.c |    3 +++
 arch/um/drivers/chan_user.c |   11 ++++++++++-
 arch/um/drivers/line.c      |    9 +++------
 3 files changed, 16 insertions(+), 7 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))
diff --git a/arch/um/drivers/chan_user.c b/arch/um/drivers/chan_user.c
index 77557e2..d29e56d 100644
--- a/arch/um/drivers/chan_user.c
+++ b/arch/um/drivers/chan_user.c
@@ -38,7 +38,16 @@ int generic_read(int fd, char *c_out, void *unused)
 
 int generic_write(int fd, const char *buf, int n, void *unused)
 {
-       return write(fd, buf, n);
+       int err;
+
+       err = write(fd, buf, n);
+       if (err > 0)
+               return err;
+       else if (errno == EAGAIN)
+               return 0;
+       else if (err == 0)
+               return -EIO;
+       return -errno;
 }
 
 int generic_window_size(int fd, void *unused, unsigned short *rows_out,
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) {
-
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Reply via email to