[PATCH 0/3] SysRq: do not pass tty argument around

[PATCH 0/3] SysRq: do not pass tty argument around

[Dmitry Torokhov]

Hi,

The following 3 patches get rid of 'tty' argument in SysRq handlers as
nobody is using it. If noone objects I'd like to get it merged through
my tree.

Thanks!

--
Dmitry

[PATCH 1/3] Input: sysrq - drop tty argument from sysrq ops handlers

[Dmitry Torokhov]

Noone is using tty argument so let's get rid of it.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---

 arch/arm/kernel/etm.c           |    2 +-
 arch/powerpc/xmon/xmon.c        |    5 ++---
 arch/sparc/kernel/process_64.c  |    2 +-
 drivers/char/sysrq.c            |   42 ++++++++++++++++++++-------------------
 drivers/gpu/drm/drm_fb_helper.c |    2 +-
 drivers/net/ibm_newemac/debug.c |    2 +-
 include/linux/sysrq.h           |    6 +++++-
 kernel/power/poweroff.c         |    2 +-
 8 files changed, 33 insertions(+), 30 deletions(-)

diff --git a/arch/arm/kernel/etm.c b/arch/arm/kernel/etm.c
index 8277539..7647593 100644
--- a/arch/arm/kernel/etm.c
+++ b/arch/arm/kernel/etm.c
@@ -230,7 +230,7 @@ static void etm_dump(void)
 	etb_lock(t);
 }
 
-static void sysrq_etm_dump(int key, struct tty_struct *tty)
+static void sysrq_etm_dump(int key)
 {
 	dev_dbg(tracer.dev, "Dumping ETB buffer\n");
 	etm_dump();
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 8bad7d5..654e155 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -2728,15 +2728,14 @@ static void xmon_init(int enable)
 }
 
 #ifdef CONFIG_MAGIC_SYSRQ
-static void sysrq_handle_xmon(int key, struct tty_struct *tty) 
+static void sysrq_handle_xmon(int key)
 {
 	/* ensure xmon is enabled */
 	xmon_init(1);
 	debugger(get_irq_regs());
 }
 
-static struct sysrq_key_op sysrq_xmon_op = 
-{
+static struct sysrq_key_op sysrq_xmon_op = {
 	.handler =	sysrq_handle_xmon,
 	.help_msg =	"Xmon",
 	.action_msg =	"Entering xmon",
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index dbe81a3..25b01b4 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -303,7 +303,7 @@ void arch_trigger_all_cpu_backtrace(void)
 
 #ifdef CONFIG_MAGIC_SYSRQ
 
-static void sysrq_handle_globreg(int key, struct tty_struct *tty)
+static void sysrq_handle_globreg(int key)
 {
 	arch_trigger_all_cpu_backtrace();
 }
diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
index 878ac0c..a892a3c 100644
--- a/drivers/char/sysrq.c
+++ b/drivers/char/sysrq.c
@@ -76,7 +76,7 @@ static int __init sysrq_always_enabled_setup(char *str)
 __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
 
 
-static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
+static void sysrq_handle_loglevel(int key)
 {
 	int i;
 
@@ -93,7 +93,7 @@ static struct sysrq_key_op sysrq_loglevel_op = {
 };
 
 #ifdef CONFIG_VT
-static void sysrq_handle_SAK(int key, struct tty_struct *tty)
+static void sysrq_handle_SAK(int key)
 {
 	struct work_struct *SAK_work = &vc_cons[fg_console].SAK_work;
 	schedule_work(SAK_work);
@@ -109,7 +109,7 @@ static struct sysrq_key_op sysrq_SAK_op = {
 #endif
 
 #ifdef CONFIG_VT
-static void sysrq_handle_unraw(int key, struct tty_struct *tty)
+static void sysrq_handle_unraw(int key)
 {
 	struct kbd_struct *kbd = &kbd_table[fg_console];
 
@@ -126,7 +126,7 @@ static struct sysrq_key_op sysrq_unraw_op = {
 #define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
 #endif /* CONFIG_VT */
 
-static void sysrq_handle_crash(int key, struct tty_struct *tty)
+static void sysrq_handle_crash(int key)
 {
 	char *killer = NULL;
 
@@ -141,7 +141,7 @@ static struct sysrq_key_op sysrq_crash_op = {
 	.enable_mask	= SYSRQ_ENABLE_DUMP,
 };
 
-static void sysrq_handle_reboot(int key, struct tty_struct *tty)
+static void sysrq_handle_reboot(int key)
 {
 	lockdep_off();
 	local_irq_enable();
@@ -154,7 +154,7 @@ static struct sysrq_key_op sysrq_reboot_op = {
 	.enable_mask	= SYSRQ_ENABLE_BOOT,
 };
 
-static void sysrq_handle_sync(int key, struct tty_struct *tty)
+static void sysrq_handle_sync(int key)
 {
 	emergency_sync();
 }
@@ -165,7 +165,7 @@ static struct sysrq_key_op sysrq_sync_op = {
 	.enable_mask	= SYSRQ_ENABLE_SYNC,
 };
 
-static void sysrq_handle_show_timers(int key, struct tty_struct *tty)
+static void sysrq_handle_show_timers(int key)
 {
 	sysrq_timer_list_show();
 }
@@ -176,7 +176,7 @@ static struct sysrq_key_op sysrq_show_timers_op = {
 	.action_msg	= "Show clockevent devices & pending hrtimers (no others)",
 };
 
-static void sysrq_handle_mountro(int key, struct tty_struct *tty)
+static void sysrq_handle_mountro(int key)
 {
 	emergency_remount();
 }
@@ -188,7 +188,7 @@ static struct sysrq_key_op sysrq_mountro_op = {
 };
 
 #ifdef CONFIG_LOCKDEP
-static void sysrq_handle_showlocks(int key, struct tty_struct *tty)
+static void sysrq_handle_showlocks(int key)
 {
 	debug_show_all_locks();
 }
@@ -226,7 +226,7 @@ static void sysrq_showregs_othercpus(struct work_struct *dummy)
 
 static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
 
-static void sysrq_handle_showallcpus(int key, struct tty_struct *tty)
+static void sysrq_handle_showallcpus(int key)
 {
 	/*
 	 * Fall back to the workqueue based printing if the
@@ -252,7 +252,7 @@ static struct sysrq_key_op sysrq_showallcpus_op = {
 };
 #endif
 
-static void sysrq_handle_showregs(int key, struct tty_struct *tty)
+static void sysrq_handle_showregs(int key)
 {
 	struct pt_regs *regs = get_irq_regs();
 	if (regs)
@@ -266,7 +266,7 @@ static struct sysrq_key_op sysrq_showregs_op = {
 	.enable_mask	= SYSRQ_ENABLE_DUMP,
 };
 
-static void sysrq_handle_showstate(int key, struct tty_struct *tty)
+static void sysrq_handle_showstate(int key)
 {
 	show_state();
 }
@@ -277,7 +277,7 @@ static struct sysrq_key_op sysrq_showstate_op = {
 	.enable_mask	= SYSRQ_ENABLE_DUMP,
 };
 
-static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)
+static void sysrq_handle_showstate_blocked(int key)
 {
 	show_state_filter(TASK_UNINTERRUPTIBLE);
 }
@@ -291,7 +291,7 @@ static struct sysrq_key_op sysrq_showstate_blocked_op = {
 #ifdef CONFIG_TRACING
 #include <linux/ftrace.h>
 
-static void sysrq_ftrace_dump(int key, struct tty_struct *tty)
+static void sysrq_ftrace_dump(int key)
 {
 	ftrace_dump(DUMP_ALL);
 }
@@ -305,7 +305,7 @@ static struct sysrq_key_op sysrq_ftrace_dump_op = {
 #define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
 #endif
 
-static void sysrq_handle_showmem(int key, struct tty_struct *tty)
+static void sysrq_handle_showmem(int key)
 {
 	show_mem();
 }
@@ -330,7 +330,7 @@ static void send_sig_all(int sig)
 	}
 }
 
-static void sysrq_handle_term(int key, struct tty_struct *tty)
+static void sysrq_handle_term(int key)
 {
 	send_sig_all(SIGTERM);
 	console_loglevel = 8;
@@ -349,7 +349,7 @@ static void moom_callback(struct work_struct *ignored)
 
 static DECLARE_WORK(moom_work, moom_callback);
 
-static void sysrq_handle_moom(int key, struct tty_struct *tty)
+static void sysrq_handle_moom(int key)
 {
 	schedule_work(&moom_work);
 }
@@ -361,7 +361,7 @@ static struct sysrq_key_op sysrq_moom_op = {
 };
 
 #ifdef CONFIG_BLOCK
-static void sysrq_handle_thaw(int key, struct tty_struct *tty)
+static void sysrq_handle_thaw(int key)
 {
 	emergency_thaw_all();
 }
@@ -373,7 +373,7 @@ static struct sysrq_key_op sysrq_thaw_op = {
 };
 #endif
 
-static void sysrq_handle_kill(int key, struct tty_struct *tty)
+static void sysrq_handle_kill(int key)
 {
 	send_sig_all(SIGKILL);
 	console_loglevel = 8;
@@ -385,7 +385,7 @@ static struct sysrq_key_op sysrq_kill_op = {
 	.enable_mask	= SYSRQ_ENABLE_SIGNAL,
 };
 
-static void sysrq_handle_unrt(int key, struct tty_struct *tty)
+static void sysrq_handle_unrt(int key)
 {
 	normalize_rt_tasks();
 }
@@ -520,7 +520,7 @@ void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
 		if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
 			printk("%s\n", op_p->action_msg);
 			console_loglevel = orig_log_level;
-			op_p->handler(key, tty);
+			op_p->handler(key);
 		} else {
 			printk("This sysrq operation is disabled.\n");
 		}
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 7196620..9598ae7 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -295,7 +295,7 @@ 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, struct tty_struct *dummy3)
+static void drm_fb_helper_sysrq(int dummy1)
 {
 	schedule_work(&drm_fb_helper_restore_work);
 }
diff --git a/drivers/net/ibm_newemac/debug.c b/drivers/net/ibm_newemac/debug.c
index 3995faf..8c6c1e2 100644
--- a/drivers/net/ibm_newemac/debug.c
+++ b/drivers/net/ibm_newemac/debug.c
@@ -238,7 +238,7 @@ void emac_dbg_dump_all(void)
 }
 
 #if defined(CONFIG_MAGIC_SYSRQ)
-static void emac_sysrq_handler(int key, struct tty_struct *tty)
+static void emac_sysrq_handler(int key)
 {
 	emac_dbg_dump_all();
 }
diff --git a/include/linux/sysrq.h b/include/linux/sysrq.h
index 609e8ca..4ee6503 100644
--- a/include/linux/sysrq.h
+++ b/include/linux/sysrq.h
@@ -31,7 +31,7 @@ struct tty_struct;
 #define SYSRQ_ENABLE_RTNICE	0x0100
 
 struct sysrq_key_op {
-	void (*handler)(int, struct tty_struct *);
+	void (*handler)(int);
 	char *help_msg;
 	char *action_msg;
 	int enable_mask;
@@ -58,6 +58,10 @@ static inline void handle_sysrq(int key, struct tty_struct *tty)
 {
 }
 
+static inline void __handle_sysrq(int key, struct tty_struct *tty, int check_mask);
+{
+}
+
 static inline int register_sysrq_key(int key, struct sysrq_key_op *op)
 {
 	return -EINVAL;
diff --git a/kernel/power/poweroff.c b/kernel/power/poweroff.c
index e8b3370..d523593 100644
--- a/kernel/power/poweroff.c
+++ b/kernel/power/poweroff.c
@@ -24,7 +24,7 @@ static void do_poweroff(struct work_struct *dummy)
 
 static DECLARE_WORK(poweroff_work, do_poweroff);
 
-static void handle_poweroff(int key, struct tty_struct *tty)
+static void handle_poweroff(int key)
 {
 	/* run sysrq poweroff on boot cpu */
 	schedule_work_on(cpumask_first(cpu_online_mask), &poweroff_work);

Re: [PATCH 1/3] Input: sysrq - drop tty argument from sysrq ops handlers

[Benjamin Herrenschmidt]

On Wed, 2010-08-04 at 00:59 -0700, Dmitry Torokhov wrote:
> Noone is using tty argument so let's get rid of it.

While talking about sysrq...

I noticed that serial drivers call sysrq with the uart lock held.

I've seen deadlocks caused by that, for example, when entering the
debugger, it waits forever for a CPU which is itself waiting on the UART
lock.

I have a patch to drop the lock in serial_core.h, I'll post that
tomorrow hopefully, just checking if there's any objection there ? The
serial drivers might need to be audited a bit to make sure they cope
with the lock being dropped and re-acquired around the sysrq call.

Cheers,
Ben.
 

Re: [PATCH 1/3] Input: sysrq - drop tty argument from sysrq ops handlers

[Alan Cox]

> I have a patch to drop the lock in serial_core.h, I'll post that
> tomorrow hopefully, just checking if there's any objection there ? The

Fundamentally - no. However the impact it has on a lot of the drivers
will be significant and you'll be submitting a huge patch pile to fix up
all the locking assumptions (for one it means port->tty might change
across any call that ends up in sysrq)

> serial drivers might need to be audited a bit to make sure they cope
> with the lock being dropped and re-acquired around the sysrq call.

Architecturally I think it would make more sense to add a new sysrq
helper which merely sets a flag, and check that flag at the end of the IRQ
when dropping the lock anyway.

Otherwise it'll be a huge amount of work to even build test all those
consoles.

Alan

Re: [PATCH 1/3] Input: sysrq - drop tty argument from sysrq ops handlers

[Benjamin Herrenschmidt]

On Wed, 2010-08-04 at 10:09 +0100, Alan Cox wrote:
> 
> Fundamentally - no. However the impact it has on a lot of the drivers
> will be significant and you'll be submitting a huge patch pile to fix up
> all the locking assumptions (for one it means port->tty might change
> across any call that ends up in sysrq)

Right. That's nasty. I think we need somewhat to break the loop when
that happens as if we were getting a new interrupt to some extent.

And that's a lot of drivers to fix.

> > serial drivers might need to be audited a bit to make sure they cope
> > with the lock being dropped and re-acquired around the sysrq call.
> 
> Architecturally I think it would make more sense to add a new sysrq
> helper which merely sets a flag, and check that flag at the end of the IRQ
> when dropping the lock anyway.

Interesting idea. That does mean that multiple sysrq in one interrupt
will be coalesced but I don't see that as an issue.

> Otherwise it'll be a huge amount of work to even build test all those
> consoles.

Right. Better to have a way where we can fix them one at a time. I'll
look into it. Thanks.

Cheers,
Ben.

Re: [PATCH 1/3] Input: sysrq - drop tty argument from sysrq ops handlers

[Jason Wessel]

On 08/04/2010 03:33 AM, Benjamin Herrenschmidt wrote:
> On Wed, 2010-08-04 at 00:59 -0700, Dmitry Torokhov wrote:
>   
>> Noone is using tty argument so let's get rid of it.
>>     
>
> While talking about sysrq...
>
> I noticed that serial drivers call sysrq with the uart lock held.
>
>   

The usb serial has the same kind of problem with all sorts of locks.  I
had resorted to using a tasklet or workqueue to get the sysrq to execute
just outside the usb serial driver context.  This work never made it
upstream because it was part of another series, but the reference is:
http://lkml.org/lkml/2010/3/9/17

For the standard serial you might be able to get away with dropping the
lock for the sysrq.

Did you have a particular way to trigger the problem or was it just
completely random, because I don't know that I have observed this
behavior with the typical 8250 driver.

Jason.

> I've seen deadlocks caused by that, for example, when entering the
> debugger, it waits forever for a CPU which is itself waiting on the UART
> lock.
>
> I have a patch to drop the lock in serial_core.h, I'll post that
> tomorrow hopefully, just checking if there's any objection there ? The
> serial drivers might need to be audited a bit to make sure they cope
> with the lock being dropped and re-acquired around the sysrq call.
>
> Cheers,
> Ben.
>  
>
>   

Re: [PATCH 1/3] Input: sysrq - drop tty argument from sysrq ops handlers

[Benjamin Herrenschmidt]

On Wed, 2010-08-04 at 07:03 -0500, Jason Wessel wrote:
> The usb serial has the same kind of problem with all sorts of locks.
> I
> had resorted to using a tasklet or workqueue to get the sysrq to
> execute
> just outside the usb serial driver context.  This work never made it
> upstream because it was part of another series, but the reference is:
> http://lkml.org/lkml/2010/3/9/17
> 
> For the standard serial you might be able to get away with dropping
> the
> lock for the sysrq.
> 
> Did you have a particular way to trigger the problem or was it just
> completely random, because I don't know that I have observed this
> behavior with the typical 8250 driver.

Yes, I do actually :-) A 64-way machine and a bunch of processes
flooding the console will do it just fine :-)

Cheers,
Ben.

[PATCH 2/3] Input: sysrq - drop tty argument form handle_sysrq()

[Dmitry Torokhov]

Sysrq operations do not accept tty argument anymore so no need to pass
it to us.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---

 arch/ia64/hp/sim/simserial.c    |    2 +-
 arch/um/drivers/mconsole_kern.c |    2 +-
 drivers/char/hangcheck-timer.c  |    2 +-
 drivers/char/hvc_console.c      |    2 +-
 drivers/char/hvsi.c             |    2 +-
 drivers/char/sysrq.c            |   11 +++++------
 drivers/s390/char/ctrlchar.c    |    4 +---
 drivers/serial/sn_console.c     |    2 +-
 drivers/usb/serial/generic.c    |    2 +-
 drivers/xen/manage.c            |    2 +-
 include/linux/serial_core.h     |    2 +-
 include/linux/sysrq.h           |   11 ++++-------
 kernel/debug/kdb/kdb_main.c     |    2 +-
 13 files changed, 20 insertions(+), 26 deletions(-)

diff --git a/arch/ia64/hp/sim/simserial.c b/arch/ia64/hp/sim/simserial.c
index 2bef526..1e8d71a 100644
--- a/arch/ia64/hp/sim/simserial.c
+++ b/arch/ia64/hp/sim/simserial.c
@@ -149,7 +149,7 @@ static  void receive_chars(struct tty_struct *tty)
 						ch = ia64_ssc(0, 0, 0, 0,
 							      SSC_GETCHAR);
 					while (!ch);
-					handle_sysrq(ch, NULL);
+					handle_sysrq(ch);
 				}
 #endif
 				seen_esc = 0;
diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index de317d0..ebc6807 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -690,7 +690,7 @@ static void with_console(struct mc_request *req, void (*proc)(void *),
 static void sysrq_proc(void *arg)
 {
 	char *op = arg;
-	handle_sysrq(*op, NULL);
+	handle_sysrq(*op);
 }
 
 void mconsole_sysrq(struct mc_request *req)
diff --git a/drivers/char/hangcheck-timer.c b/drivers/char/hangcheck-timer.c
index e024972..f953c96 100644
--- a/drivers/char/hangcheck-timer.c
+++ b/drivers/char/hangcheck-timer.c
@@ -159,7 +159,7 @@ static void hangcheck_fire(unsigned long data)
 		if (hangcheck_dump_tasks) {
 			printk(KERN_CRIT "Hangcheck: Task state:\n");
 #ifdef CONFIG_MAGIC_SYSRQ
-			handle_sysrq('t', NULL);
+			handle_sysrq('t');
 #endif  /* CONFIG_MAGIC_SYSRQ */
 		}
 		if (hangcheck_reboot) {
diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
index 35cca4c..1f99a6f 100644
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -651,7 +651,7 @@ int hvc_poll(struct hvc_struct *hp)
 					if (sysrq_pressed)
 						continue;
 				} else if (sysrq_pressed) {
-					handle_sysrq(buf[i], tty);
+					handle_sysrq(buf[i]);
 					sysrq_pressed = 0;
 					continue;
 				}
diff --git a/drivers/char/hvsi.c b/drivers/char/hvsi.c
index d4b14ff..8620f7d 100644
--- a/drivers/char/hvsi.c
+++ b/drivers/char/hvsi.c
@@ -403,7 +403,7 @@ static void hvsi_insert_chars(struct hvsi_struct *hp, const char *buf, int len)
 			hp->sysrq = 1;
 			continue;
 		} else if (hp->sysrq) {
-			handle_sysrq(c, hp->tty);
+			handle_sysrq(c);
 			hp->sysrq = 0;
 			continue;
 		}
diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
index a892a3c..ef31bb8 100644
--- a/drivers/char/sysrq.c
+++ b/drivers/char/sysrq.c
@@ -18,7 +18,6 @@
 #include <linux/interrupt.h>
 #include <linux/mm.h>
 #include <linux/fs.h>
-#include <linux/tty.h>
 #include <linux/mount.h>
 #include <linux/kdev_t.h>
 #include <linux/major.h>
@@ -493,7 +492,7 @@ static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
                 sysrq_key_table[i] = op_p;
 }
 
-void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
+void __handle_sysrq(int key, bool check_mask)
 {
 	struct sysrq_key_op *op_p;
 	int orig_log_level;
@@ -545,10 +544,10 @@ void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
 	spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 }
 
-void handle_sysrq(int key, struct tty_struct *tty)
+void handle_sysrq(int key)
 {
 	if (sysrq_on())
-		__handle_sysrq(key, tty, 1);
+		__handle_sysrq(key, true);
 }
 EXPORT_SYMBOL(handle_sysrq);
 
@@ -597,7 +596,7 @@ static bool sysrq_filter(struct input_handle *handle, unsigned int type,
 
 	default:
 		if (sysrq_down && value && value != 2)
-			__handle_sysrq(sysrq_xlate[code], NULL, 1);
+			__handle_sysrq(sysrq_xlate[code], true);
 		break;
 	}
 
@@ -765,7 +764,7 @@ static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
 
 		if (get_user(c, buf))
 			return -EFAULT;
-		__handle_sysrq(c, NULL, 0);
+		__handle_sysrq(c, false);
 	}
 
 	return count;
diff --git a/drivers/s390/char/ctrlchar.c b/drivers/s390/char/ctrlchar.c
index c6cbcb3..0e9a309 100644
--- a/drivers/s390/char/ctrlchar.c
+++ b/drivers/s390/char/ctrlchar.c
@@ -16,12 +16,11 @@
 
 #ifdef CONFIG_MAGIC_SYSRQ
 static int ctrlchar_sysrq_key;
-static struct tty_struct *sysrq_tty;
 
 static void
 ctrlchar_handle_sysrq(struct work_struct *work)
 {
-	handle_sysrq(ctrlchar_sysrq_key, sysrq_tty);
+	handle_sysrq(ctrlchar_sysrq_key);
 }
 
 static DECLARE_WORK(ctrlchar_work, ctrlchar_handle_sysrq);
@@ -54,7 +53,6 @@ ctrlchar_handle(const unsigned char *buf, int len, struct tty_struct *tty)
 	/* racy */
 	if (len == 3 && buf[1] == '-') {
 		ctrlchar_sysrq_key = buf[2];
-		sysrq_tty = tty;
 		schedule_work(&ctrlchar_work);
 		return CTRLCHAR_SYSRQ;
 	}
diff --git a/drivers/serial/sn_console.c b/drivers/serial/sn_console.c
index 9794e0c..4924108 100644
--- a/drivers/serial/sn_console.c
+++ b/drivers/serial/sn_console.c
@@ -492,7 +492,7 @@ sn_receive_chars(struct sn_cons_port *port, unsigned long flags)
                         sysrq_requested = 0;
                         if (ch && time_before(jiffies, sysrq_timeout)) {
                                 spin_unlock_irqrestore(&port->sc_port.lock, flags);
-                                handle_sysrq(ch, NULL);
+                                handle_sysrq(ch);
                                 spin_lock_irqsave(&port->sc_port.lock, flags);
                                 /* ignore actual sysrq command char */
                                 continue;
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index a817ced..9587c22 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -448,7 +448,7 @@ int usb_serial_handle_sysrq_char(struct tty_struct *tty,
 {
 	if (port->sysrq && port->port.console) {
 		if (ch && time_before(jiffies, port->sysrq)) {
-			handle_sysrq(ch, tty);
+			handle_sysrq(ch);
 			port->sysrq = 0;
 			return 1;
 		}
diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 07e857b..3896719 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -212,7 +212,7 @@ static void sysrq_handler(struct xenbus_watch *watch, const char **vec,
 		goto again;
 
 	if (sysrq_key != '\0')
-		handle_sysrq(sysrq_key, NULL);
+		handle_sysrq(sysrq_key);
 }
 
 static struct xenbus_watch sysrq_watch = {
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index f10db6e..1faf49d 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -453,7 +453,7 @@ uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
 #ifdef SUPPORT_SYSRQ
 	if (port->sysrq) {
 		if (ch && time_before(jiffies, port->sysrq)) {
-			handle_sysrq(ch, port->state->port.tty);
+			handle_sysrq(ch);
 			port->sysrq = 0;
 			return 1;
 		}
diff --git a/include/linux/sysrq.h b/include/linux/sysrq.h
index 4ee6503..32d360a 100644
--- a/include/linux/sysrq.h
+++ b/include/linux/sysrq.h
@@ -16,9 +16,6 @@
 
 #include <linux/errno.h>
 
-struct pt_regs;
-struct tty_struct;
-
 /* Possible values of bitmask for enabling sysrq functions */
 /* 0x0001 is reserved for enable everything */
 #define SYSRQ_ENABLE_LOG	0x0002
@@ -44,8 +41,8 @@ struct sysrq_key_op {
  * are available -- else NULL's).
  */
 
-void handle_sysrq(int key, struct tty_struct *tty);
-void __handle_sysrq(int key, struct tty_struct *tty, int check_mask);
+void handle_sysrq(int key);
+void __handle_sysrq(int key, bool check_mask);
 int register_sysrq_key(int key, struct sysrq_key_op *op);
 int unregister_sysrq_key(int key, struct sysrq_key_op *op);
 struct sysrq_key_op *__sysrq_get_key_op(int key);
@@ -54,11 +51,11 @@ int sysrq_toggle_support(int enable_mask);
 
 #else
 
-static inline void handle_sysrq(int key, struct tty_struct *tty)
+static inline void handle_sysrq(int key)
 {
 }
 
-static inline void __handle_sysrq(int key, struct tty_struct *tty, int check_mask);
+static inline void __handle_sysrq(int key, bool check_mask)
 {
 }
 
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index ebe4a28..4768998 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -1821,7 +1821,7 @@ static int kdb_sr(int argc, const char **argv)
 	if (argc != 1)
 		return KDB_ARGCOUNT;
 	kdb_trap_printk++;
-	__handle_sysrq(*argv[1], NULL, 0);
+	__handle_sysrq(*argv[1], false);
 	kdb_trap_printk--;
 
 	return 0;

Re: [PATCH 2/3] Input: sysrq - drop tty argument form handle_sysrq()

[Jason Wessel]

On 08/04/2010 02:59 AM, Dmitry Torokhov wrote:
> Sysrq operations do not accept tty argument anymore so no need to pass
> it to us.
>
> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
>   

Looks fine to me.  The kernel debugger was passing NULL anyway because
A) it was not going to be easy to figure out the tty at the time, and B)
the sysrq was not using the tty at the lowest level.

Acked-by: Jason Wessel <jason.wessel@windriver.com>

[PATCH 3/3] USB: drop tty argument from usb_serial_handle_sysrq_char()

[Dmitry Torokhov]

Since handle_sysrq() does not take tty as argument anymore we can
drop it from usb_serial_handle_sysrq_char() as well.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---

 drivers/usb/serial/ftdi_sio.c |    2 +-
 drivers/usb/serial/generic.c  |    5 ++---
 drivers/usb/serial/pl2303.c   |    2 +-
 include/linux/usb/serial.h    |    3 +--
 4 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index e298dc4..8aecfe5 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1827,7 +1827,7 @@ static int ftdi_process_packet(struct tty_struct *tty,
 
 	if (port->port.console && port->sysrq) {
 		for (i = 0; i < len; i++, ch++) {
-			if (!usb_serial_handle_sysrq_char(tty, port, *ch))
+			if (!usb_serial_handle_sysrq_char(port, *ch))
 				tty_insert_flip_char(tty, *ch, flag);
 		}
 	} else {
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 9587c22..dee73b9 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -338,7 +338,7 @@ void usb_serial_generic_process_read_urb(struct urb *urb)
 		tty_insert_flip_string(tty, ch, urb->actual_length);
 	else {
 		for (i = 0; i < urb->actual_length; i++, ch++) {
-			if (!usb_serial_handle_sysrq_char(tty, port, *ch))
+			if (!usb_serial_handle_sysrq_char(port, *ch))
 				tty_insert_flip_char(tty, *ch, TTY_NORMAL);
 		}
 	}
@@ -443,8 +443,7 @@ void usb_serial_generic_unthrottle(struct tty_struct *tty)
 EXPORT_SYMBOL_GPL(usb_serial_generic_unthrottle);
 
 #ifdef CONFIG_MAGIC_SYSRQ
-int usb_serial_handle_sysrq_char(struct tty_struct *tty,
-			struct usb_serial_port *port, unsigned int ch)
+int usb_serial_handle_sysrq_char(struct usb_serial_port *port, unsigned int ch)
 {
 	if (port->sysrq && port->port.console) {
 		if (ch && time_before(jiffies, port->sysrq)) {
diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 6b60018..34ad7b3 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -788,7 +788,7 @@ static void pl2303_process_read_urb(struct urb *urb)
 
 	if (port->port.console && port->sysrq) {
 		for (i = 0; i < urb->actual_length; ++i)
-			if (!usb_serial_handle_sysrq_char(tty, port, data[i]))
+			if (!usb_serial_handle_sysrq_char(port, data[i]))
 				tty_insert_flip_char(tty, data[i], tty_flag);
 	} else {
 		tty_insert_flip_string_fixed_flag(tty, data, tty_flag,
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 84a4c44..55675b1 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -342,8 +342,7 @@ extern int usb_serial_generic_submit_read_urb(struct usb_serial_port *port,
 extern void usb_serial_generic_process_read_urb(struct urb *urb);
 extern int usb_serial_generic_prepare_write_buffer(struct usb_serial_port *port,
 						void *dest, size_t size);
-extern int usb_serial_handle_sysrq_char(struct tty_struct *tty,
-					struct usb_serial_port *port,
+extern int usb_serial_handle_sysrq_char(struct usb_serial_port *port,
 					unsigned int ch);
 extern int usb_serial_handle_break(struct usb_serial_port *port);
 

Re: [PATCH 3/3] USB: drop tty argument from usb_serial_handle_sysrq_char()

[Jason Wessel]

On 08/04/2010 02:59 AM, Dmitry Torokhov wrote:
> Since handle_sysrq() does not take tty as argument anymore we can
> drop it from usb_serial_handle_sysrq_char() as well.
>
>   

Acked-by: Jason Wessel <jason.wessel@windriver.com>

Re: [PATCH 0/3] SysRq: do not pass tty argument around

[Alan Cox]

On Wed, 04 Aug 2010 00:58:55 -0700
Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:

> Hi,
> 
> The following 3 patches get rid of 'tty' argument in SysRq handlers as
> nobody is using it. If noone objects I'd like to get it merged through
> my tree.

Looks good to me.

Re: [PATCH 0/3] SysRq: do not pass tty argument around

[Greg KH]

On Wed, Aug 04, 2010 at 12:58:55AM -0700, Dmitry Torokhov wrote:
> Hi,
> 
> The following 3 patches get rid of 'tty' argument in SysRq handlers as
> nobody is using it. If noone objects I'd like to get it merged through
> my tree.

Nice job.

No objection from me for you to take this through your tree:
	Acked-by: Greg Kroah-Hartman <gregkh@suse.de>

thanks,

greg k-h