Messages in this thread | | | Date | Fri, 17 Mar 2023 14:23:16 +0100 | Subject | Re: [PATCH v2] hvc/xen: prevent concurrent accesses to the shared ring | From | Juergen Gross <> |
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On 30.11.22 16:09, Roger Pau Monne wrote: > The hvc machinery registers both a console and a tty device based on > the hv ops provided by the specific implementation. Those two > interfaces however have different locks, and there's no single locks > that's shared between the tty and the console implementations, hence > the driver needs to protect itself against concurrent accesses. > Otherwise concurrent calls using the split interfaces are likely to > corrupt the ring indexes, leaving the console unusable. > > Introduce a lock to xencons_info to serialize accesses to the shared > ring. This is only required when using the shared memory console, > concurrent accesses to the hypercall based console implementation are > not an issue. > > Note the conditional logic in domU_read_console() is slightly modified > so the notify_daemon() call can be done outside of the locked region: > it's an hypercall and there's no need for it to be done with the lock > held. > > Fixes: b536b4b96230 ('xen: use the hvc console infrastructure for Xen console') > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Juergen
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