um: chan_user: catch EINTR when reading and writing

If the read/write function returns an error then we expect to see an
event/IRQ later on. However, this will only happen after an EAGAIN as we
are using edge based event triggering.

As such, EINTR needs to be caught should it happen.
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20231018123643.1255813-2-benjamin@sipsolutions.netSigned-off-by: Johannes Berg <johannes.berg@intel.com>

arch/um/drivers/chan_user.c

@@ -23,7 +23,7 @@ int generic_read(int fd, __u8 *c_out, void *unused)
 {
 	int n;
 
-	n = read(fd, c_out, sizeof(*c_out));
+	CATCH_EINTR(n = read(fd, c_out, sizeof(*c_out)));
 	if (n > 0)
 		return n;
 	else if (n == 0)
@@ -39,7 +39,7 @@ int generic_write(int fd, const __u8 *buf, size_t n, void *unused)
 {
 	int err;
 
-	err = write(fd, buf, n);
+	CATCH_EINTR(err = write(fd, buf, n));
 	if (err > 0)
 		return err;
 	else if (errno == EAGAIN)