From: Doug Dumitru <[email protected]>
I have been fighting a buffering error when sending large amounts of
data out pty devices from UML. I have tried a couple of patches that
did not really fix the problem (and were rightly rejected by the group),
but have finally found the real bug.
In /arch/um/drivers/line.c there is a function "buffer_data" that is
responsible for storing data into the lines ring buffer. The function
is "supposed" to return the number of characters actually buffered.
Unfortunately, in the case where the buffer wraps, the "len" variable is
decremented by "end" before it is used as the return parameter.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <[email protected]>
Signed-off-by: Jeff Dike <[email protected]>
Index: linux-2.6.9-rc2-mm1-orig/arch/um/drivers/line.c
===================================================================
--- linux-2.6.9-rc2-mm1-orig.orig/arch/um/drivers/line.c 2004-09-22 20:39:58.000000000 -0400
+++ linux-2.6.9-rc2-mm1-orig/arch/um/drivers/line.c 2004-09-22 20:55:34.000000000 -0400
@@ -73,9 +73,8 @@
else {
memcpy(line->tail, buf, end);
buf += end;
- len -= end;
- memcpy(line->buffer, buf, len);
- line->tail = line->buffer + len;
+ memcpy(line->buffer, buf, len - end);
+ line->tail = line->buffer + len - end;
}
return(len);