stable inclusion
from stable-v5.10.164
commit 92b30a27e4fa5929d94d863dc1eb27b231590016
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7T7G4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=92b30a27e4fa5929d94d863dc1eb27b231590016

--------------------------------

[ Upstream commit c0dccad8 ]

The currently lockless access to the xen console list in
vtermno_to_xencons() is incorrect, as additions and removals from the
list can happen anytime, and as such the traversal of the list to get
the private console data for a given termno needs to happen with the
lock held.  Note users that modify the list already do so with the
lock taken.

Adjust current lock takers to use the _irq{save,restore} helpers,
since the context in which vtermno_to_xencons() is called can have
interrupts disabled.  Use the _irq{save,restore} set of helpers to
switch the current callers to disable interrupts in the locked region.
I haven't checked if existing users could instead use the _irq
variant, as I think it's safer to use _irq{save,restore} upfront.

While there switch from using list_for_each_entry_safe to
list_for_each_entry: the current entry cursor won't be removed as
part of the code in the loop body, so using the _safe variant is
pointless.

Fixes: 02e19f9c ('hvc_xen: implement multiconsole support')
Signed-off-by: NRoger Pau Monné <roger.pau@citrix.com>
Reviewed-by: NStefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/20221130163611.14686-1-roger.pau@citrix.comSigned-off-by: NJuergen Gross <jgross@suse.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: Nsanglipeng <sanglipeng1@jd.com>