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linux/drivers/tty/hvc
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Roger Pau Monne f6003784b1 hvc/xen: lock console list traversal 
[ Upstream commit c0dccad87c ]

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: 02e19f9c7c ('hvc_xen: implement multiconsole support')
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/20221130163611.14686-1-roger.pau@citrix.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-01-18 11:48:54 +01:00
..
hvc_console.c tty: drop put_tty_driver 2021-07-27 12:17:21 +02:00
hvc_console.h tty: hvc: Use the correct style for SPDX License Identifier 2020-03-18 13:01:05 +01:00
hvc_dcc.c hvc: dcc: Add earlycon support 2019-10-11 08:38:07 +02:00
hvc_irq.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hvc_iucv.c tty: hvc: fix return value of __setup handler 2022-04-08 14:23:50 +02:00
hvc_opal.c tty: hvc: hvc_opal: Staticify function invoked by reference 2020-11-06 10:54:05 +01:00
hvc_riscv_sbi.c tty: Don't force RISCV SBI console as preferred console 2019-05-16 20:42:11 -07:00
hvc_rtas.c tty: hvc: Remove redundant license text 2017-11-08 13:08:12 +01:00
hvc_udbg.c tty: hvc: make symbol 'hvc_udbg_dev' static 2021-04-10 10:41:40 +02:00
hvc_vio.c tty: hvc: udbg_hvc: retry putc on -EAGAIN 2021-05-23 20:51:36 +10:00
hvc_xen.c hvc/xen: lock console list traversal 2023-01-18 11:48:54 +01:00
hvcs.c tty: drop put_tty_driver 2021-07-27 12:17:21 +02:00
hvsi.c tty: stop using alloc_tty_driver 2021-07-27 12:17:20 +02:00
hvsi_lib.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig tty: hvc: fix link error with CONFIG_SERIAL_CORE_CONSOLE=n 2020-09-27 14:17:43 +02:00
Makefile TTY/Serial driver patches for 4.17-rc1 2018-04-04 18:43:49 -07:00