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Re: [PATCH v2] xen/hvc: replace BUG_ON() with negative return value

On 07.07.21 11:57, Jan Beulich wrote:
On 07.07.2021 11:10, Juergen Gross wrote:
Xen frontends shouldn't BUG() in case of illegal data received from
their backends. So replace the BUG_ON()s when reading illegal data from
the ring page with negative return values.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -86,7 +86,11 @@ static int __write_console(struct xencons_info *xencons,
        cons = intf->out_cons;
        prod = intf->out_prod;
        mb();                   /* update queue values before going on */

Largely unrelated note: While in general the barriers here may want
switching to virt_*mb(), this particular one looks to be too heavy
anyway: a read barrier is all that's needed here afaict, just like
there's only a write barrier between ring contents and producer
writing in __write_console().

I agree.

And btw, since I've got puzzled by the linuxppc-dev@ in the recipients
list, I did look up relevant entries in ./MAINTAINERS. Shouldn't the

I wouldn't mind. Greg, Jiri, what do you think?


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