[v2] cpu,sched: Mark arch_cpu_idle_dead() __noreturn

[PATCH v2 10/24] mips/cpu: Make sure play_dead() doesn't return

Posted by Josh Poimboeuf 2 years, 6 months ago

play_dead() doesn't return.  Make that more explicit with a BUG().

BUG() is preferable to unreachable() because BUG() is a more explicit
failure mode and avoids undefined behavior like falling off the edge of
the function into whatever code happens to be next.

Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 arch/mips/kernel/smp-bmips.c | 2 ++
 arch/mips/loongson64/smp.c   | 1 +
 2 files changed, 3 insertions(+)

diff --git a/arch/mips/kernel/smp-bmips.c b/arch/mips/kernel/smp-bmips.c
index df9158e8329d..be85fa075830 100644
--- a/arch/mips/kernel/smp-bmips.c
+++ b/arch/mips/kernel/smp-bmips.c
@@ -414,6 +414,8 @@ void __ref play_dead(void)
 	"	wait\n"
 	"	j	bmips_secondary_reentry\n"
 	: : : "memory");
+
+	BUG();
 }
 
 #endif /* CONFIG_HOTPLUG_CPU */
diff --git a/arch/mips/loongson64/smp.c b/arch/mips/loongson64/smp.c
index 660e1de4412a..c81c2bd07c62 100644
--- a/arch/mips/loongson64/smp.c
+++ b/arch/mips/loongson64/smp.c
@@ -822,6 +822,7 @@ void play_dead(void)
 	state_addr = &per_cpu(cpu_state, cpu);
 	mb();
 	play_dead_at_ckseg1(state_addr);
+	BUG();
 }
 
 static int loongson3_disable_clock(unsigned int cpu)
-- 
2.39.1

Re: [PATCH v2 10/24] mips/cpu: Make sure play_dead() doesn't return

Posted by Philippe Mathieu-Daudé 2 years, 6 months ago

On 14/2/23 08:05, Josh Poimboeuf wrote:
> play_dead() doesn't return.  Make that more explicit with a BUG().
> 
> BUG() is preferable to unreachable() because BUG() is a more explicit
> failure mode and avoids undefined behavior like falling off the edge of
> the function into whatever code happens to be next.
> 
> Acked-by: Florian Fainelli <f.fainelli@gmail.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
>   arch/mips/kernel/smp-bmips.c | 2 ++
>   arch/mips/loongson64/smp.c   | 1 +
>   2 files changed, 3 insertions(+)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

[tip: objtool/core] mips/cpu: Make sure play_dead() doesn't return

Posted by tip-bot2 for Josh Poimboeuf 2 years, 6 months ago

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     a80ceed6c9c24088d7a2e3c414eae1fe88a8ccbe
Gitweb:        https://git.kernel.org/tip/a80ceed6c9c24088d7a2e3c414eae1fe88a8ccbe
Author:        Josh Poimboeuf <jpoimboe@kernel.org>
AuthorDate:    Mon, 13 Feb 2023 23:05:44 -08:00
Committer:     Josh Poimboeuf <jpoimboe@kernel.org>
CommitterDate: Wed, 08 Mar 2023 08:44:23 -08:00

mips/cpu: Make sure play_dead() doesn't return

play_dead() doesn't return.  Make that more explicit with a BUG().

BUG() is preferable to unreachable() because BUG() is a more explicit
failure mode and avoids undefined behavior like falling off the edge of
the function into whatever code happens to be next.

Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Link: https://lore.kernel.org/r/b195e4da190bb06b7d4af15d66ce6129e2347630.1676358308.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 arch/mips/kernel/smp-bmips.c | 2 ++
 arch/mips/loongson64/smp.c   | 1 +
 2 files changed, 3 insertions(+)

diff --git a/arch/mips/kernel/smp-bmips.c b/arch/mips/kernel/smp-bmips.c
index 51d5dae..15466d4 100644
--- a/arch/mips/kernel/smp-bmips.c
+++ b/arch/mips/kernel/smp-bmips.c
@@ -415,6 +415,8 @@ void __ref play_dead(void)
 	"	wait\n"
 	"	j	bmips_secondary_reentry\n"
 	: : : "memory");
+
+	BUG();
 }
 
 #endif /* CONFIG_HOTPLUG_CPU */
diff --git a/arch/mips/loongson64/smp.c b/arch/mips/loongson64/smp.c
index 4e24b31..df8d789 100644
--- a/arch/mips/loongson64/smp.c
+++ b/arch/mips/loongson64/smp.c
@@ -823,6 +823,7 @@ out:
 	state_addr = &per_cpu(cpu_state, cpu);
 	mb();
 	play_dead_at_ckseg1(state_addr);
+	BUG();
 }
 
 static int loongson3_disable_clock(unsigned int cpu)