* [PATCH] ARM: hide finish_arch_post_lock_switch from modules
@ 2016-05-13 13:30 ` Arnd Bergmann
0 siblings, 0 replies; 5+ messages in thread
From: Arnd Bergmann @ 2016-05-13 13:30 UTC (permalink / raw)
To: Ingo Molnar
Cc: Andy Lutomirski, Steven Rostedt, Russell King - ARM Linux,
Guenter Roeck, Ard Biesheuvel, Peter Zijlstra,
Frederic Weisbecker, linux-kernel, Andy Lutomirski,
Thomas Gleixner, Borislav Petkov, Mel Gorman, linux-arm-kernel,
Arnd Bergmann
From: Steven Rostedt <rostedt@goodmis.org>
The introduction of switch_mm_irqs_off() brought back an old bug
regarding the use of preempt_enable_no_resched:
As part of 62b94a08da1b ("sched/preempt: Take away
preempt_enable_no_resched() from modules"), the definition of
preempt_enable_no_resched() is only available in built-in code,
not in loadable modules, so we can't generally use it from header
files. However, the ARM version of finish_arch_post_lock_switch()
calls preempt_enable_no_resched() and is defined as a static
inline function in asm/mmu_context.h. This in turn means we cannot
include asm/mmu_context.h from modules.
With today's tip tree, asm/mmu_context.h gets included from
linux/mmu_context.h, which is normally the exact pattern one would
expect, but unfortunately, linux/mmu_context.h can be included from
the vhost driver that is a loadable module, now causing this compile
time error:
In file included from ../include/linux/mmu_context.h:4:0,
from ../drivers/vhost/vhost.c:18:
../arch/arm/include/asm/mmu_context.h: In function 'finish_arch_post_lock_switch':
../arch/arm/include/asm/mmu_context.h:88:3: error: implicit declaration of function 'preempt_enable_no_resched' [-Werror=implicit-function-declaration]
preempt_enable_no_resched();
Andy already tried to fix the bug by including linux/preempt.h
from asm/mmu_context.h, but that didn't help. I suggested reordering
the header files, which wasn't popular, but Steve came up with this
workaround instead:
The finish_arch_post_lock_switch() definition is now also hidden
inside of #ifdef MODULE, so we don't see anything referencing
preempt_enable_no_resched() from a header file. I've built a
few hundred randconfig kernels with this, and did not see any
new problems.
Fixes: f98db6013c55 ("sched/core: Add switch_mm_irqs_off() and use it in the scheduler")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
arch/arm/include/asm/mmu_context.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
index ed73babc0dc9..3cc14dd8587c 100644
--- a/arch/arm/include/asm/mmu_context.h
+++ b/arch/arm/include/asm/mmu_context.h
@@ -67,6 +67,7 @@ static inline void check_and_switch_context(struct mm_struct *mm,
cpu_switch_mm(mm->pgd, mm);
}
+#ifndef MODULE
#define finish_arch_post_lock_switch \
finish_arch_post_lock_switch
static inline void finish_arch_post_lock_switch(void)
@@ -88,6 +89,7 @@ static inline void finish_arch_post_lock_switch(void)
preempt_enable_no_resched();
}
}
+#endif /* !MODULE */
#endif /* CONFIG_MMU */
--
2.7.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH] ARM: hide finish_arch_post_lock_switch from modules
2016-05-13 13:30 ` Arnd Bergmann
@ 2016-05-13 13:51 ` Guenter Roeck
-1 siblings, 0 replies; 5+ messages in thread
From: Guenter Roeck @ 2016-05-13 13:51 UTC (permalink / raw)
To: linux-arm-kernel
On 05/13/2016 06:30 AM, Arnd Bergmann wrote:
> From: Steven Rostedt <rostedt@goodmis.org>
>
> The introduction of switch_mm_irqs_off() brought back an old bug
> regarding the use of preempt_enable_no_resched:
>
> As part of 62b94a08da1b ("sched/preempt: Take away
> preempt_enable_no_resched() from modules"), the definition of
> preempt_enable_no_resched() is only available in built-in code,
> not in loadable modules, so we can't generally use it from header
> files. However, the ARM version of finish_arch_post_lock_switch()
> calls preempt_enable_no_resched() and is defined as a static
> inline function in asm/mmu_context.h. This in turn means we cannot
> include asm/mmu_context.h from modules.
>
> With today's tip tree, asm/mmu_context.h gets included from
> linux/mmu_context.h, which is normally the exact pattern one would
> expect, but unfortunately, linux/mmu_context.h can be included from
> the vhost driver that is a loadable module, now causing this compile
> time error:
>
> In file included from ../include/linux/mmu_context.h:4:0,
> from ../drivers/vhost/vhost.c:18:
> ../arch/arm/include/asm/mmu_context.h: In function 'finish_arch_post_lock_switch':
> ../arch/arm/include/asm/mmu_context.h:88:3: error: implicit declaration of function 'preempt_enable_no_resched' [-Werror=implicit-function-declaration]
> preempt_enable_no_resched();
>
> Andy already tried to fix the bug by including linux/preempt.h
> from asm/mmu_context.h, but that didn't help. I suggested reordering
> the header files, which wasn't popular, but Steve came up with this
> workaround instead:
>
> The finish_arch_post_lock_switch() definition is now also hidden
> inside of #ifdef MODULE, so we don't see anything referencing
> preempt_enable_no_resched() from a header file. I've built a
> few hundred randconfig kernels with this, and did not see any
> new problems.
>
> Fixes: f98db6013c55 ("sched/core: Add switch_mm_irqs_off() and use it in the scheduler")
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Guenter Roeck <linux@roeck-us.net>
> ---
> arch/arm/include/asm/mmu_context.h | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
> index ed73babc0dc9..3cc14dd8587c 100644
> --- a/arch/arm/include/asm/mmu_context.h
> +++ b/arch/arm/include/asm/mmu_context.h
> @@ -67,6 +67,7 @@ static inline void check_and_switch_context(struct mm_struct *mm,
> cpu_switch_mm(mm->pgd, mm);
> }
>
> +#ifndef MODULE
> #define finish_arch_post_lock_switch \
> finish_arch_post_lock_switch
> static inline void finish_arch_post_lock_switch(void)
> @@ -88,6 +89,7 @@ static inline void finish_arch_post_lock_switch(void)
> preempt_enable_no_resched();
> }
> }
> +#endif /* !MODULE */
>
> #endif /* CONFIG_MMU */
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] ARM: hide finish_arch_post_lock_switch from modules
@ 2016-05-13 13:51 ` Guenter Roeck
0 siblings, 0 replies; 5+ messages in thread
From: Guenter Roeck @ 2016-05-13 13:51 UTC (permalink / raw)
To: Arnd Bergmann, Ingo Molnar
Cc: Andy Lutomirski, Steven Rostedt, Russell King - ARM Linux,
Ard Biesheuvel, Peter Zijlstra, Frederic Weisbecker, linux-kernel,
Andy Lutomirski, Thomas Gleixner, Borislav Petkov, Mel Gorman,
linux-arm-kernel
On 05/13/2016 06:30 AM, Arnd Bergmann wrote:
> From: Steven Rostedt <rostedt@goodmis.org>
>
> The introduction of switch_mm_irqs_off() brought back an old bug
> regarding the use of preempt_enable_no_resched:
>
> As part of 62b94a08da1b ("sched/preempt: Take away
> preempt_enable_no_resched() from modules"), the definition of
> preempt_enable_no_resched() is only available in built-in code,
> not in loadable modules, so we can't generally use it from header
> files. However, the ARM version of finish_arch_post_lock_switch()
> calls preempt_enable_no_resched() and is defined as a static
> inline function in asm/mmu_context.h. This in turn means we cannot
> include asm/mmu_context.h from modules.
>
> With today's tip tree, asm/mmu_context.h gets included from
> linux/mmu_context.h, which is normally the exact pattern one would
> expect, but unfortunately, linux/mmu_context.h can be included from
> the vhost driver that is a loadable module, now causing this compile
> time error:
>
> In file included from ../include/linux/mmu_context.h:4:0,
> from ../drivers/vhost/vhost.c:18:
> ../arch/arm/include/asm/mmu_context.h: In function 'finish_arch_post_lock_switch':
> ../arch/arm/include/asm/mmu_context.h:88:3: error: implicit declaration of function 'preempt_enable_no_resched' [-Werror=implicit-function-declaration]
> preempt_enable_no_resched();
>
> Andy already tried to fix the bug by including linux/preempt.h
> from asm/mmu_context.h, but that didn't help. I suggested reordering
> the header files, which wasn't popular, but Steve came up with this
> workaround instead:
>
> The finish_arch_post_lock_switch() definition is now also hidden
> inside of #ifdef MODULE, so we don't see anything referencing
> preempt_enable_no_resched() from a header file. I've built a
> few hundred randconfig kernels with this, and did not see any
> new problems.
>
> Fixes: f98db6013c55 ("sched/core: Add switch_mm_irqs_off() and use it in the scheduler")
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Guenter Roeck <linux@roeck-us.net>
> ---
> arch/arm/include/asm/mmu_context.h | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
> index ed73babc0dc9..3cc14dd8587c 100644
> --- a/arch/arm/include/asm/mmu_context.h
> +++ b/arch/arm/include/asm/mmu_context.h
> @@ -67,6 +67,7 @@ static inline void check_and_switch_context(struct mm_struct *mm,
> cpu_switch_mm(mm->pgd, mm);
> }
>
> +#ifndef MODULE
> #define finish_arch_post_lock_switch \
> finish_arch_post_lock_switch
> static inline void finish_arch_post_lock_switch(void)
> @@ -88,6 +89,7 @@ static inline void finish_arch_post_lock_switch(void)
> preempt_enable_no_resched();
> }
> }
> +#endif /* !MODULE */
>
> #endif /* CONFIG_MMU */
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* [tip:sched/core] ARM: Hide finish_arch_post_lock_switch() from modules
2016-05-13 13:30 ` Arnd Bergmann
(?)
(?)
@ 2016-05-13 14:15 ` tip-bot for Steven Rostedt
-1 siblings, 0 replies; 5+ messages in thread
From: tip-bot for Steven Rostedt @ 2016-05-13 14:15 UTC (permalink / raw)
To: linux-tip-commits
Cc: torvalds, eranian, acme, tglx, alexander.shishkin, bp,
ard.biesheuvel, rostedt, hpa, mingo, jolsa, arnd, linux, luto,
linux, vincent.weaver, rmk+kernel, fweisbec, luto, mgorman,
linux-kernel, peterz
Commit-ID: ef0491ea17f8019821c7e9c8e801184ecf17f85a
Gitweb: http://git.kernel.org/tip/ef0491ea17f8019821c7e9c8e801184ecf17f85a
Author: Steven Rostedt <rostedt@goodmis.org>
AuthorDate: Fri, 13 May 2016 15:30:13 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 13 May 2016 16:12:53 +0200
ARM: Hide finish_arch_post_lock_switch() from modules
The introduction of switch_mm_irqs_off() brought back an old bug
regarding the use of preempt_enable_no_resched:
As part of:
62b94a08da1b ("sched/preempt: Take away preempt_enable_no_resched() from modules")
the definition of preempt_enable_no_resched() is only available in
built-in code, not in loadable modules, so we can't generally use
it from header files.
However, the ARM version of finish_arch_post_lock_switch()
calls preempt_enable_no_resched() and is defined as a static
inline function in asm/mmu_context.h. This in turn means we cannot
include asm/mmu_context.h from modules.
With today's tip tree, asm/mmu_context.h gets included from
linux/mmu_context.h, which is normally the exact pattern one would
expect, but unfortunately, linux/mmu_context.h can be included from
the vhost driver that is a loadable module, now causing this compile
time error with modular configs:
In file included from ../include/linux/mmu_context.h:4:0,
from ../drivers/vhost/vhost.c:18:
../arch/arm/include/asm/mmu_context.h: In function 'finish_arch_post_lock_switch':
../arch/arm/include/asm/mmu_context.h:88:3: error: implicit declaration of function 'preempt_enable_no_resched' [-Werror=implicit-function-declaration]
preempt_enable_no_resched();
Andy already tried to fix the bug by including linux/preempt.h
from asm/mmu_context.h, but that didn't help. Arnd suggested reordering
the header files, which wasn't popular, so let's use this
workaround instead:
The finish_arch_post_lock_switch() definition is now also hidden
inside of #ifdef MODULE, so we don't see anything referencing
preempt_enable_no_resched() from a header file. I've built a
few hundred randconfig kernels with this, and did not see any
new problems.
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux <linux@armlinux.org.uk>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-arm-kernel@lists.infradead.org
Fixes: f98db6013c55 ("sched/core: Add switch_mm_irqs_off() and use it in the scheduler")
Link: http://lkml.kernel.org/r/1463146234-161304-1-git-send-email-arnd@arndb.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/arm/include/asm/mmu_context.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
index ed73bab..3cc14dd 100644
--- a/arch/arm/include/asm/mmu_context.h
+++ b/arch/arm/include/asm/mmu_context.h
@@ -67,6 +67,7 @@ static inline void check_and_switch_context(struct mm_struct *mm,
cpu_switch_mm(mm->pgd, mm);
}
+#ifndef MODULE
#define finish_arch_post_lock_switch \
finish_arch_post_lock_switch
static inline void finish_arch_post_lock_switch(void)
@@ -88,6 +89,7 @@ static inline void finish_arch_post_lock_switch(void)
preempt_enable_no_resched();
}
}
+#endif /* !MODULE */
#endif /* CONFIG_MMU */
^ permalink raw reply related [flat|nested] 5+ messages in thread