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Thu, 25 Apr 2019 09:59:57 +0000 (UTC) Delivered-To: dm-devel@redhat.com Received: from mx1.redhat.com (ext-mx19.extmail.prod.ext.phx2.redhat.com [10.5.110.48]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F06635D9C5; Thu, 25 Apr 2019 09:59:50 +0000 (UTC) Received: from Galois.linutronix.de (Galois.linutronix.de [146.0.238.70]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 90DC6307D85B; Thu, 25 Apr 2019 09:59:49 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1hJb9k-0001qX-9I; Thu, 25 Apr 2019 11:59:04 +0200 Message-Id: <20190425094801.230654524@linutronix.de> User-Agent: quilt/0.65 Date: Thu, 25 Apr 2019 11:44:54 +0200 From: Thomas Gleixner To: LKML References: <20190425094453.875139013@linutronix.de> MIME-Version: 1.0 X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Thu, 25 Apr 2019 09:59:50 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Thu, 25 Apr 2019 09:59:50 +0000 (UTC) for IP:'146.0.238.70' DOMAIN:'Galois.linutronix.de' HELO:'Galois.linutronix.de' FROM:'tglx@linutronix.de' RCPT:'' X-RedHat-Spam-Score: 0 () 146.0.238.70 Galois.linutronix.de 146.0.238.70 Galois.linutronix.de X-Scanned-By: MIMEDefang 2.84 on 10.5.110.48 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Thu, 25 Apr 2019 09:29:28 -0400 Cc: Mike Snitzer , David Airlie , Catalin Marinas , Joonas Lahtinen , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, dm-devel@redhat.com, Alexander Potapenko , Christoph Lameter , Miroslav Benes , Christoph Hellwig , Alasdair Kergon , Marek Szyprowski , linux-arch@vger.kernel.org, x86@kernel.org, kasan-dev@googlegroups.com, Johannes Thumshirn , Andrey Ryabinin , Alexey Dobriyan , intel-gfx@lists.freedesktop.org, David Rientjes , Maarten Lankhorst , Akinobu Mita , Steven Rostedt , Josef Bacik , Rodrigo Vivi , Mike Rapoport , Jani Nikula , Andy Lutomirski , Josh Poimboeuf , David Sterba , Dmitry Vyukov , Tom Zanussi , Chris Mason , Pekka Enberg , iommu@lists.linux-foundation.org, Daniel Vetter , Andrew Morton , Robin Murphy , linux-btrfs@vger.kernel.org Subject: [dm-devel] [patch V3 01/29] tracing: Cleanup stack trace code X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Thu, 25 Apr 2019 13:29:47 +0000 (UTC) X-Virus-Scanned: ClamAV using ClamSMTP - Remove the extra array member of stack_dump_trace[] along with the ARRAY_SIZE - 1 initialization for struct stack_trace :: max_entries. Both are historical leftovers of no value. The stack tracer never exceeds the array and there is no extra storage requirement either. - Make variables which are only used in trace_stack.c static. - Simplify the enable/disable logic. - Rename stack_trace_print() as it's using the stack_trace_ namespace. Free the name up for stack trace related functions. Signed-off-by: Thomas Gleixner Reviewed-by: Steven Rostedt --- V3: Remove the -1 init and split the variable declaration as requested by Steven. V2: Add more cleanups and use print_max_stack() as requested by Steven. --- include/linux/ftrace.h | 18 ++++-------------- kernel/trace/trace_stack.c | 42 +++++++++++++----------------------------- 2 files changed, 17 insertions(+), 43 deletions(-) -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -241,21 +241,11 @@ static inline void ftrace_free_mem(struc #ifdef CONFIG_STACK_TRACER -#define STACK_TRACE_ENTRIES 500 - -struct stack_trace; - -extern unsigned stack_trace_index[]; -extern struct stack_trace stack_trace_max; -extern unsigned long stack_trace_max_size; -extern arch_spinlock_t stack_trace_max_lock; - extern int stack_tracer_enabled; -void stack_trace_print(void); -int -stack_trace_sysctl(struct ctl_table *table, int write, - void __user *buffer, size_t *lenp, - loff_t *ppos); + +int stack_trace_sysctl(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos); /* DO NOT MODIFY THIS VARIABLE DIRECTLY! */ DECLARE_PER_CPU(int, disable_stack_tracer); --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -18,30 +18,26 @@ #include "trace.h" -static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES + 1]; -unsigned stack_trace_index[STACK_TRACE_ENTRIES]; +#define STACK_TRACE_ENTRIES 500 + +static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES]; +static unsigned stack_trace_index[STACK_TRACE_ENTRIES]; -/* - * Reserve one entry for the passed in ip. This will allow - * us to remove most or all of the stack size overhead - * added by the stack tracer itself. - */ struct stack_trace stack_trace_max = { - .max_entries = STACK_TRACE_ENTRIES - 1, + .max_entries = STACK_TRACE_ENTRIES, .entries = &stack_dump_trace[0], }; -unsigned long stack_trace_max_size; -arch_spinlock_t stack_trace_max_lock = +static unsigned long stack_trace_max_size; +static arch_spinlock_t stack_trace_max_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; DEFINE_PER_CPU(int, disable_stack_tracer); static DEFINE_MUTEX(stack_sysctl_mutex); int stack_tracer_enabled; -static int last_stack_tracer_enabled; -void stack_trace_print(void) +static void print_max_stack(void) { long i; int size; @@ -61,16 +57,7 @@ void stack_trace_print(void) } } -/* - * When arch-specific code overrides this function, the following - * data should be filled up, assuming stack_trace_max_lock is held to - * prevent concurrent updates. - * stack_trace_index[] - * stack_trace_max - * stack_trace_max_size - */ -void __weak -check_stack(unsigned long ip, unsigned long *stack) +static void check_stack(unsigned long ip, unsigned long *stack) { unsigned long this_size, flags; unsigned long *p, *top, *start; static int tracer_frame; @@ -179,7 +166,7 @@ check_stack(unsigned long ip, unsigned l stack_trace_max.nr_entries = x; if (task_stack_end_corrupted(current)) { - stack_trace_print(); + print_max_stack(); BUG(); } @@ -412,23 +399,21 @@ stack_trace_sysctl(struct ctl_table *tab void __user *buffer, size_t *lenp, loff_t *ppos) { + int was_enabled; int ret; mutex_lock(&stack_sysctl_mutex); + was_enabled = !!stack_tracer_enabled; ret = proc_dointvec(table, write, buffer, lenp, ppos); - if (ret || !write || - (last_stack_tracer_enabled == !!stack_tracer_enabled)) + if (ret || !write || (was_enabled == !!stack_tracer_enabled)) goto out; - last_stack_tracer_enabled = !!stack_tracer_enabled; - if (stack_tracer_enabled) register_ftrace_function(&trace_ops); else unregister_ftrace_function(&trace_ops); - out: mutex_unlock(&stack_sysctl_mutex); return ret; @@ -444,7 +429,6 @@ static __init int enable_stacktrace(char strncpy(stack_trace_filter_buf, str + len, COMMAND_LINE_SIZE); stack_tracer_enabled = 1; - last_stack_tracer_enabled = 1; return 1; } __setup("stacktrace", enable_stacktrace);