bunch of quoting for context:
> > other 10 are questionable. Those 10 are all simple variations on the
> > following code:
> >
> > Start --->
> > if (!tmp_buf) {
> > page = get_free_page(GFP_KERNEL);
> >
> > Error --->
> > if (tmp_buf)
> > free_page(page);
> > else
> > tmp_buf = (unsigned char *) page;
> > }
>
> That one is not a bug. The serial drivers do this to handle a race. Really
> it should be
>
> page = get_free_page(GFP_KERNEL)
>
> rmb();
> if (tmp_buf)
> ..
>
> but this will go away as and when someone switches the tty layer to new
> style locking. The precise code flow (under lock_kernel in both cases) is
>
>
> if (!tmp_buf)
> {
> /* tmp_buf was 0
> page = get_free_page (...)
> [SLEEPS, TASK SWITCH]
>
Does this mean that the 'cli' in the following code is redundant?
/* 2.4.7/drivers/char/generic_serial.c:953:gs_init_port: */
if (!tmp_buf) {
page = get_free_page(GFP_KERNEL);
cli (); /* Don't expect this to make a difference. */
if (tmp_buf)
free_page(page);
else
tmp_buf = (unsigned char *) page;
Dawson
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Tue Jul 31 2001 - 21:00:25 EST