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a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1624533111; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1w6rpiEgwhZVgRsqWlcOzTrH9OZ5OS60CHHCp1sLrGw=; b=pfZ3OpGuG59GBQCXX5cSXH9ubMmhLeJkhw94xtJInYHKrzr0AdOR306fJLgDRRR9fs4sz+ c+BtjlWhKhPbonAg== To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Russell King , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Ingo Molnar , Marc Zyngier , Valentin Schneider , Andrew Morton , Pekka Enberg , Mike Rapoport , "Wolfram Sang (Renesas)" , Anshuman Khandual , Peter Zijlstra , Frederic Weisbecker , Kees Cook , Masahiro Yamada , Nathan Chancellor , Sami Tolvanen , Alexei Starovoitov , Nick Terrell , Chris Wilson , Vlastimil Babka , linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org Subject: [PATCH printk v3 4/6] printk: remove NMI tracking Date: Thu, 24 Jun 2021 13:17:46 +0206 Message-Id: <20210624111148.5190-5-john.ogness@linutronix.de> In-Reply-To: <20210624111148.5190-1-john.ogness@linutronix.de> References: <20210624111148.5190-1-john.ogness@linutronix.de> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210624_041203_662537_444B255C X-CRM114-Status: GOOD ( 16.50 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org All NMI contexts are handled the same as the safe context: store the message and defer printing. There is no need to have special NMI context tracking for this. Using in_nmi() is enough. Signed-off-by: John Ogness Reviewed-by: Petr Mladek --- arch/arm/kernel/smp.c | 2 -- arch/powerpc/kexec/crash.c | 3 --- include/linux/hardirq.h | 2 -- include/linux/printk.h | 12 ------------ init/Kconfig | 5 ----- kernel/printk/internal.h | 6 ------ kernel/printk/printk_safe.c | 37 +------------------------------------ kernel/trace/trace.c | 2 -- 8 files changed, 1 insertion(+), 68 deletions(-) diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 74679240a9d8..0dd2d733ad62 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -668,9 +668,7 @@ static void do_handle_IPI(int ipinr) break; case IPI_CPU_BACKTRACE: - printk_nmi_enter(); nmi_cpu_backtrace(get_irq_regs()); - printk_nmi_exit(); break; default: diff --git a/arch/powerpc/kexec/crash.c b/arch/powerpc/kexec/crash.c index c9a889880214..d488311efab1 100644 --- a/arch/powerpc/kexec/crash.c +++ b/arch/powerpc/kexec/crash.c @@ -311,9 +311,6 @@ void default_machine_crash_shutdown(struct pt_regs *regs) unsigned int i; int (*old_handler)(struct pt_regs *regs); - /* Avoid hardlocking with irresponsive CPU holding logbuf_lock */ - printk_nmi_enter(); - /* * This function is only called after the system * has panicked or is otherwise in a critical state. diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h index 69bc86ea382c..76878b357ffa 100644 --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -116,7 +116,6 @@ extern void rcu_nmi_exit(void); do { \ lockdep_off(); \ arch_nmi_enter(); \ - printk_nmi_enter(); \ BUG_ON(in_nmi() == NMI_MASK); \ __preempt_count_add(NMI_OFFSET + HARDIRQ_OFFSET); \ } while (0) @@ -135,7 +134,6 @@ extern void rcu_nmi_exit(void); do { \ BUG_ON(!in_nmi()); \ __preempt_count_sub(NMI_OFFSET + HARDIRQ_OFFSET); \ - printk_nmi_exit(); \ arch_nmi_exit(); \ lockdep_on(); \ } while (0) diff --git a/include/linux/printk.h b/include/linux/printk.h index 664612f75dac..14a18fa15c92 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -149,18 +149,6 @@ static inline __printf(1, 2) __cold void early_printk(const char *s, ...) { } #endif -#ifdef CONFIG_PRINTK_NMI -extern void printk_nmi_enter(void); -extern void printk_nmi_exit(void); -extern void printk_nmi_direct_enter(void); -extern void printk_nmi_direct_exit(void); -#else -static inline void printk_nmi_enter(void) { } -static inline void printk_nmi_exit(void) { } -static inline void printk_nmi_direct_enter(void) { } -static inline void printk_nmi_direct_exit(void) { } -#endif /* PRINTK_NMI */ - struct dev_printk_info; #ifdef CONFIG_PRINTK diff --git a/init/Kconfig b/init/Kconfig index 5babea38e346..4053588db7a0 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1488,11 +1488,6 @@ config PRINTK very difficult to diagnose system problems, saying N here is strongly discouraged. -config PRINTK_NMI - def_bool y - depends on PRINTK - depends on HAVE_NMI - config BUG bool "BUG() support" if EXPERT default y diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h index 6cc35c5de890..ff890ae3ee6a 100644 --- a/kernel/printk/internal.h +++ b/kernel/printk/internal.h @@ -6,12 +6,6 @@ #ifdef CONFIG_PRINTK -#define PRINTK_SAFE_CONTEXT_MASK 0x007ffffff -#define PRINTK_NMI_DIRECT_CONTEXT_MASK 0x008000000 -#define PRINTK_NMI_CONTEXT_MASK 0xff0000000 - -#define PRINTK_NMI_CONTEXT_OFFSET 0x010000000 - __printf(4, 0) int vprintk_store(int facility, int level, const struct dev_printk_info *dev_info, diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c index 0456cd48d01c..47d961149a06 100644 --- a/kernel/printk/printk_safe.c +++ b/kernel/printk/printk_safe.c @@ -4,12 +4,9 @@ */ #include -#include -#include #include #include #include -#include #include #include @@ -17,35 +14,6 @@ static DEFINE_PER_CPU(int, printk_context); -#ifdef CONFIG_PRINTK_NMI -void noinstr printk_nmi_enter(void) -{ - this_cpu_add(printk_context, PRINTK_NMI_CONTEXT_OFFSET); -} - -void noinstr printk_nmi_exit(void) -{ - this_cpu_sub(printk_context, PRINTK_NMI_CONTEXT_OFFSET); -} - -/* - * Marks a code that might produce many messages in NMI context - * and the risk of losing them is more critical than eventual - * reordering. - */ -void printk_nmi_direct_enter(void) -{ - if (this_cpu_read(printk_context) & PRINTK_NMI_CONTEXT_MASK) - this_cpu_or(printk_context, PRINTK_NMI_DIRECT_CONTEXT_MASK); -} - -void printk_nmi_direct_exit(void) -{ - this_cpu_and(printk_context, ~PRINTK_NMI_DIRECT_CONTEXT_MASK); -} - -#endif /* CONFIG_PRINTK_NMI */ - /* Can be preempted by NMI. */ void __printk_safe_enter(void) { @@ -70,10 +38,7 @@ asmlinkage int vprintk(const char *fmt, va_list args) * Use the main logbuf even in NMI. But avoid calling console * drivers that might have their own locks. */ - if (this_cpu_read(printk_context) & - (PRINTK_NMI_DIRECT_CONTEXT_MASK | - PRINTK_NMI_CONTEXT_MASK | - PRINTK_SAFE_CONTEXT_MASK)) { + if (this_cpu_read(printk_context) || in_nmi()) { unsigned long flags; int len; diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 915fe8790f04..6ac254f7a04c 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -9409,7 +9409,6 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) tracing_off(); local_irq_save(flags); - printk_nmi_direct_enter(); /* Simulate the iterator */ trace_init_global_iter(&iter); @@ -9491,7 +9490,6 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) atomic_dec(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); } atomic_dec(&dump_running); - printk_nmi_direct_exit(); local_irq_restore(flags); } EXPORT_SYMBOL_GPL(ftrace_dump);