Re: [PATCH 02/10] tty: sysrq: switch sysrq handlers from int to u8

From: Paul E. McKenney
Date: Wed Jul 12 2023 - 09:37:31 EST

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On Wed, Jul 12, 2023 at 10:18:03AM +0200, Jiri Slaby (SUSE) wrote:
> The passed parameter to sysrq handlers is a key (a character). So change
> the type from 'int' to 'u8'. Let it specifically be 'u8' for two
> reasons:
> * unsigned: unsigned values come from the upper layers (devices) and the
> tty layer assumes unsigned on most places, and
> * 8-bit: as that what's supposed to be one day in all the layers built
> on the top of tty. (Currently, we use mostly 'unsigned char' and
> somewhere still only 'char'. (But that also translates to the former
> thanks to -funsigned-char.))
>
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@xxxxxxxxxx>
> Cc: Richard Henderson <richard.henderson@xxxxxxxxxx>
> Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>
> Cc: Matt Turner <mattst88@xxxxxxxxx>
> Cc: Huacai Chen <chenhuacai@xxxxxxxxxx>
> Cc: WANG Xuerui <kernel@xxxxxxxxxx>
> Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
> Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Cc: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
> Cc: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
> Cc: Douglas Anderson <dianders@xxxxxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
> Cc: Len Brown <len.brown@xxxxxxxxx>
> Cc: Pavel Machek <pavel@xxxxxx>
> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
> Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
> Cc: Neeraj Upadhyay <quic_neeraju@xxxxxxxxxxx>
> Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
> Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
> Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
> Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
> Cc: Zqiang <qiang.zhang1211@xxxxxxxxx>

>From an RCU perspective:

Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxx>

> ---
> arch/alpha/kernel/setup.c | 2 +-
> arch/loongarch/kernel/sysrq.c | 2 +-
> arch/mips/kernel/sysrq.c | 2 +-
> arch/powerpc/xmon/xmon.c | 2 +-
> arch/sparc/kernel/process_64.c | 4 ++--
> drivers/gpu/drm/drm_fb_helper.c | 2 +-
> drivers/tty/sysrq.c | 40 ++++++++++++++++-----------------
> include/linux/sysrq.h | 2 +-
> kernel/debug/debug_core.c | 2 +-
> kernel/power/poweroff.c | 2 +-
> kernel/rcu/tree_stall.h | 2 +-
> 11 files changed, 31 insertions(+), 31 deletions(-)
>
> diff --git a/arch/alpha/kernel/setup.c b/arch/alpha/kernel/setup.c
> index b650ff1cb022..91fb3714ebc2 100644
> --- a/arch/alpha/kernel/setup.c
> +++ b/arch/alpha/kernel/setup.c
> @@ -422,7 +422,7 @@ register_cpus(void)
> arch_initcall(register_cpus);
>
> #ifdef CONFIG_MAGIC_SYSRQ
> -static void sysrq_reboot_handler(int unused)
> +static void sysrq_reboot_handler(u8 unused)
> {
> machine_halt();
> }
> diff --git a/arch/loongarch/kernel/sysrq.c b/arch/loongarch/kernel/sysrq.c
> index 366baef72d29..e663c10fa39c 100644
> --- a/arch/loongarch/kernel/sysrq.c
> +++ b/arch/loongarch/kernel/sysrq.c
> @@ -43,7 +43,7 @@ static void sysrq_tlbdump_othercpus(struct work_struct *dummy)
> static DECLARE_WORK(sysrq_tlbdump, sysrq_tlbdump_othercpus);
> #endif
>
> -static void sysrq_handle_tlbdump(int key)
> +static void sysrq_handle_tlbdump(u8 key)
> {
> sysrq_tlbdump_single(NULL);
> #ifdef CONFIG_SMP
> diff --git a/arch/mips/kernel/sysrq.c b/arch/mips/kernel/sysrq.c
> index 9c1a2019113b..2e98049fe783 100644
> --- a/arch/mips/kernel/sysrq.c
> +++ b/arch/mips/kernel/sysrq.c
> @@ -44,7 +44,7 @@ static void sysrq_tlbdump_othercpus(struct work_struct *dummy)
> static DECLARE_WORK(sysrq_tlbdump, sysrq_tlbdump_othercpus);
> #endif
>
> -static void sysrq_handle_tlbdump(int key)
> +static void sysrq_handle_tlbdump(u8 key)
> {
> sysrq_tlbdump_single(NULL);
> #ifdef CONFIG_SMP
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index ee17270d35d0..3b6f524c790e 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -3991,7 +3991,7 @@ static void xmon_init(int enable)
> }
>
> #ifdef CONFIG_MAGIC_SYSRQ
> -static void sysrq_handle_xmon(int key)
> +static void sysrq_handle_xmon(u8 key)
> {
> if (xmon_is_locked_down()) {
> clear_all_bpt();
> diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
> index b51d8fb0ecdc..4dee88af403f 100644
> --- a/arch/sparc/kernel/process_64.c
> +++ b/arch/sparc/kernel/process_64.c
> @@ -295,7 +295,7 @@ void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
>
> #ifdef CONFIG_MAGIC_SYSRQ
>
> -static void sysrq_handle_globreg(int key)
> +static void sysrq_handle_globreg(u8 key)
> {
> trigger_all_cpu_backtrace();
> }
> @@ -370,7 +370,7 @@ static void pmu_snapshot_all_cpus(void)
> spin_unlock_irqrestore(&global_cpu_snapshot_lock, flags);
> }
>
> -static void sysrq_handle_globpmu(int key)
> +static void sysrq_handle_globpmu(u8 key)
> {
> pmu_snapshot_all_cpus();
> }
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 61a5d450cc20..d612133e2cf7 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -301,7 +301,7 @@ static void drm_fb_helper_restore_work_fn(struct work_struct *ignored)
>
> static DECLARE_WORK(drm_fb_helper_restore_work, drm_fb_helper_restore_work_fn);
>
> -static void drm_fb_helper_sysrq(int dummy1)
> +static void drm_fb_helper_sysrq(u8 dummy1)
> {
> schedule_work(&drm_fb_helper_restore_work);
> }
> diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
> index 13465e4cca9b..1271a82c0887 100644
> --- a/drivers/tty/sysrq.c
> +++ b/drivers/tty/sysrq.c
> @@ -98,7 +98,7 @@ static int __init sysrq_always_enabled_setup(char *str)
> __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
>
>
> -static void sysrq_handle_loglevel(int key)
> +static void sysrq_handle_loglevel(u8 key)
> {
> u8 loglevel = key - '0';
>
> @@ -114,7 +114,7 @@ static const struct sysrq_key_op sysrq_loglevel_op = {
> };
>
> #ifdef CONFIG_VT
> -static void sysrq_handle_SAK(int key)
> +static void sysrq_handle_SAK(u8 key)
> {
> struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
>
> @@ -131,7 +131,7 @@ static const struct sysrq_key_op sysrq_SAK_op = {
> #endif
>
> #ifdef CONFIG_VT
> -static void sysrq_handle_unraw(int key)
> +static void sysrq_handle_unraw(u8 key)
> {
> vt_reset_unicode(fg_console);
> }
> @@ -146,7 +146,7 @@ static const struct sysrq_key_op sysrq_unraw_op = {
> #define sysrq_unraw_op (*(const struct sysrq_key_op *)NULL)
> #endif /* CONFIG_VT */
>
> -static void sysrq_handle_crash(int key)
> +static void sysrq_handle_crash(u8 key)
> {
> /* release the RCU read lock before crashing */
> rcu_read_unlock();
> @@ -160,7 +160,7 @@ static const struct sysrq_key_op sysrq_crash_op = {
> .enable_mask = SYSRQ_ENABLE_DUMP,
> };
>
> -static void sysrq_handle_reboot(int key)
> +static void sysrq_handle_reboot(u8 key)
> {
> lockdep_off();
> local_irq_enable();
> @@ -175,7 +175,7 @@ static const struct sysrq_key_op sysrq_reboot_op = {
>
> const struct sysrq_key_op *__sysrq_reboot_op = &sysrq_reboot_op;
>
> -static void sysrq_handle_sync(int key)
> +static void sysrq_handle_sync(u8 key)
> {
> emergency_sync();
> }
> @@ -186,7 +186,7 @@ static const struct sysrq_key_op sysrq_sync_op = {
> .enable_mask = SYSRQ_ENABLE_SYNC,
> };
>
> -static void sysrq_handle_show_timers(int key)
> +static void sysrq_handle_show_timers(u8 key)
> {
> sysrq_timer_list_show();
> }
> @@ -197,7 +197,7 @@ static const struct sysrq_key_op sysrq_show_timers_op = {
> .action_msg = "Show clockevent devices & pending hrtimers (no others)",
> };
>
> -static void sysrq_handle_mountro(int key)
> +static void sysrq_handle_mountro(u8 key)
> {
> emergency_remount();
> }
> @@ -209,7 +209,7 @@ static const struct sysrq_key_op sysrq_mountro_op = {
> };
>
> #ifdef CONFIG_LOCKDEP
> -static void sysrq_handle_showlocks(int key)
> +static void sysrq_handle_showlocks(u8 key)
> {
> debug_show_all_locks();
> }
> @@ -249,7 +249,7 @@ static void sysrq_showregs_othercpus(struct work_struct *dummy)
>
> static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
>
> -static void sysrq_handle_showallcpus(int key)
> +static void sysrq_handle_showallcpus(u8 key)
> {
> /*
> * Fall back to the workqueue based printing if the
> @@ -282,7 +282,7 @@ static const struct sysrq_key_op sysrq_showallcpus_op = {
> #define sysrq_showallcpus_op (*(const struct sysrq_key_op *)NULL)
> #endif
>
> -static void sysrq_handle_showregs(int key)
> +static void sysrq_handle_showregs(u8 key)
> {
> struct pt_regs *regs = NULL;
>
> @@ -299,7 +299,7 @@ static const struct sysrq_key_op sysrq_showregs_op = {
> .enable_mask = SYSRQ_ENABLE_DUMP,
> };
>
> -static void sysrq_handle_showstate(int key)
> +static void sysrq_handle_showstate(u8 key)
> {
> show_state();
> show_all_workqueues();
> @@ -311,7 +311,7 @@ static const struct sysrq_key_op sysrq_showstate_op = {
> .enable_mask = SYSRQ_ENABLE_DUMP,
> };
>
> -static void sysrq_handle_showstate_blocked(int key)
> +static void sysrq_handle_showstate_blocked(u8 key)
> {
> show_state_filter(TASK_UNINTERRUPTIBLE);
> }
> @@ -325,7 +325,7 @@ static const struct sysrq_key_op sysrq_showstate_blocked_op = {
> #ifdef CONFIG_TRACING
> #include <linux/ftrace.h>
>
> -static void sysrq_ftrace_dump(int key)
> +static void sysrq_ftrace_dump(u8 key)
> {
> ftrace_dump(DUMP_ALL);
> }
> @@ -339,7 +339,7 @@ static const struct sysrq_key_op sysrq_ftrace_dump_op = {
> #define sysrq_ftrace_dump_op (*(const struct sysrq_key_op *)NULL)
> #endif
>
> -static void sysrq_handle_showmem(int key)
> +static void sysrq_handle_showmem(u8 key)
> {
> show_mem();
> }
> @@ -369,7 +369,7 @@ static void send_sig_all(int sig)
> read_unlock(&tasklist_lock);
> }
>
> -static void sysrq_handle_term(int key)
> +static void sysrq_handle_term(u8 key)
> {
> send_sig_all(SIGTERM);
> console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
> @@ -400,7 +400,7 @@ static void moom_callback(struct work_struct *ignored)
>
> static DECLARE_WORK(moom_work, moom_callback);
>
> -static void sysrq_handle_moom(int key)
> +static void sysrq_handle_moom(u8 key)
> {
> schedule_work(&moom_work);
> }
> @@ -412,7 +412,7 @@ static const struct sysrq_key_op sysrq_moom_op = {
> };
>
> #ifdef CONFIG_BLOCK
> -static void sysrq_handle_thaw(int key)
> +static void sysrq_handle_thaw(u8 key)
> {
> emergency_thaw_all();
> }
> @@ -426,7 +426,7 @@ static const struct sysrq_key_op sysrq_thaw_op = {
> #define sysrq_thaw_op (*(const struct sysrq_key_op *)NULL)
> #endif
>
> -static void sysrq_handle_kill(int key)
> +static void sysrq_handle_kill(u8 key)
> {
> send_sig_all(SIGKILL);
> console_loglevel = CONSOLE_LOGLEVEL_DEBUG;
> @@ -438,7 +438,7 @@ static const struct sysrq_key_op sysrq_kill_op = {
> .enable_mask = SYSRQ_ENABLE_SIGNAL,
> };
>
> -static void sysrq_handle_unrt(int key)
> +static void sysrq_handle_unrt(u8 key)
> {
> normalize_rt_tasks();
> }
> diff --git a/include/linux/sysrq.h b/include/linux/sysrq.h
> index 3a582ec7a2f1..bb8d07814b0e 100644
> --- a/include/linux/sysrq.h
> +++ b/include/linux/sysrq.h
> @@ -30,7 +30,7 @@
> #define SYSRQ_ENABLE_RTNICE 0x0100
>
> struct sysrq_key_op {
> - void (* const handler)(int);
> + void (* const handler)(u8);
> const char * const help_msg;
> const char * const action_msg;
> const int enable_mask;
> diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
> index d5e9ccde3ab8..621037a0aa87 100644
> --- a/kernel/debug/debug_core.c
> +++ b/kernel/debug/debug_core.c
> @@ -968,7 +968,7 @@ static int __init opt_kgdb_con(char *str)
> early_param("kgdbcon", opt_kgdb_con);
>
> #ifdef CONFIG_MAGIC_SYSRQ
> -static void sysrq_handle_dbg(int key)
> +static void sysrq_handle_dbg(u8 key)
> {
> if (!dbg_io_ops) {
> pr_crit("ERROR: No KGDB I/O module available\n");
> diff --git a/kernel/power/poweroff.c b/kernel/power/poweroff.c
> index 562aa0e450ed..1f306f158696 100644
> --- a/kernel/power/poweroff.c
> +++ b/kernel/power/poweroff.c
> @@ -23,7 +23,7 @@ static void do_poweroff(struct work_struct *dummy)
>
> static DECLARE_WORK(poweroff_work, do_poweroff);
>
> -static void handle_poweroff(int key)
> +static void handle_poweroff(u8 key)
> {
> /* run sysrq poweroff on boot cpu */
> schedule_work_on(cpumask_first(cpu_online_mask), &poweroff_work);
> diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
> index b10b8349bb2a..6f06dc12904a 100644
> --- a/kernel/rcu/tree_stall.h
> +++ b/kernel/rcu/tree_stall.h
> @@ -1035,7 +1035,7 @@ static bool sysrq_rcu;
> module_param(sysrq_rcu, bool, 0444);
>
> /* Dump grace-period-request information due to commandeered sysrq. */
> -static void sysrq_show_rcu(int key)
> +static void sysrq_show_rcu(u8 key)
> {
> show_rcu_gp_kthreads();
> }
> --
> 2.41.0
>

Next message: Martin Povišer: "[PATCH 1/2] dt-bindings: dma: apple,sio: Add schema"
Previous message: Christian König: "Re: Memory providers multiplexing (Was: [PATCH net-next v4 4/5] page_pool: remove PP_FLAG_PAGE_FRAG flag)"
In reply to: Thomas Zimmermann: "Re: [PATCH 02/10] tty: sysrq: switch sysrq handlers from int to u8"
Next in thread: Daniel Thompson: "Re: [PATCH 02/10] tty: sysrq: switch sysrq handlers from int to u8"
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