Hi,
On 09/15/2010 03:46 PM, Amit Shah wrote:
On (Wed) Sep 15 2010 [15:37:21], Hans de Goede wrote:
--- linux-2.6.35.x86_64/drivers/char/virtio_console.c~ 2010-08-02 00:11:14.000000000 +0200
+++ linux-2.6.35.x86_64/drivers/char/virtio_console.c 2010-09-15 13:39:29.043505000 +0200
@@ -642,7 +642,7 @@ static unsigned int port_fops_poll(struc
poll_wait(filp,&port->waitqueue, wait);
ret = 0;
- if (port->inbuf)
+ if (!will_read_block(port))
Looks correct, but this should be
if (port_has_data(port))
instead.
That certainly works for me (as in will still fix the bug I'm hitting), but
quoting from "man 2 select":
Three independent sets of file descriptors are watched. Those listed
in readfds will be watched to see if characters become available for
reading (more precisely, to see if a read will not block; in particu‐
lar, a file descriptor is also ready on end-of-file)
Notice the "a file descriptor is also ready on end-of-file", and
port_fops_read treats the host not being connected as eof (it returns 0
in that case). So from an API pov I'm not sure what is correct.
poll(2) says:
POLLIN There is data to read.
That makes it simple.
Also, we also set POLLHUP in case the host is disconnected, so if host
is not connected while there's data to read, we'll get POLLIN|POLLHUP in
revents, and further reads will be blocked.
Ah, I completely missed the POLLHUP getting set thingie. I guess that will
get used by the kernel to also not block if any fds have it said in select's
readfds argument.
One new patch coming up!
Regards,
Hans
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