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Peter Anvin" , Andy Lutomirski , Peter Zijlstra , "Rob Herring" , Steven Rostedt , "Andrew Morton" , Mark Rutland , "Tom Lendacky" , Ashish Kalra , James Gowans , Stanislav Kinsburskii , , , , Anthony Yznaga , Usama Arif , David Woodhouse , Benjamin Herrenschmidt Subject: [PATCH 08/15] tracing: Introduce names for ring buffers Date: Wed, 13 Dec 2023 00:04:45 +0000 Message-ID: <20231213000452.88295-9-graf@amazon.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231213000452.88295-1-graf@amazon.com> References: <20231213000452.88295-1-graf@amazon.com> MIME-Version: 1.0 X-Originating-IP: [10.253.83.51] X-ClientProxiedBy: EX19D042UWA003.ant.amazon.com (10.13.139.44) To EX19D020UWC004.ant.amazon.com (10.13.138.149) X-Rspamd-Queue-Id: 0BD611A001E X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: ciz1y1f5kb5p6rjonsoeyh3d3zxgsk4t X-HE-Tag: 1702425993-652350 X-HE-Meta: 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 TH8iWgmX 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: With KHO (Kexec HandOver), we want to preserve trace buffers across kexec. To carry over their state between kernels, the kernel needs a common handle for them that exists on both sides. As handle we introduce names for ring buffers. In a follow-up patch, the kernel can then use these names to recover buffer contents for specific ring buffers. Signed-off-by: Alexander Graf --- include/linux/ring_buffer.h | 7 ++++--- kernel/trace/ring_buffer.c | 5 ++++- kernel/trace/trace.c | 7 ++++--- 3 files changed, 12 insertions(+), 7 deletions(-) diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 782e14f62201..f34538f97c75 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -85,17 +85,18 @@ void ring_buffer_discard_commit(struct trace_buffer *buffer, * size is in bytes for each per CPU buffer. */ struct trace_buffer * -__ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key); +__ring_buffer_alloc(const char *name, unsigned long size, unsigned flags, + struct lock_class_key *key); /* * Because the ring buffer is generic, if other users of the ring buffer get * traced by ftrace, it can produce lockdep warnings. We need to keep each * ring buffer's lock class separate. */ -#define ring_buffer_alloc(size, flags) \ +#define ring_buffer_alloc(name, size, flags) \ ({ \ static struct lock_class_key __key; \ - __ring_buffer_alloc((size), (flags), &__key); \ + __ring_buffer_alloc((name), (size), (flags), &__key); \ }) int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full); diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 43cc47d7faaf..eaaf823ddedb 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -557,6 +557,7 @@ struct trace_buffer { struct rb_irq_work irq_work; bool time_stamp_abs; + const char *name; }; struct ring_buffer_iter { @@ -1801,7 +1802,8 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) * when the buffer wraps. If this flag is not set, the buffer will * drop data when the tail hits the head. */ -struct trace_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, +struct trace_buffer *__ring_buffer_alloc(const char *name, + unsigned long size, unsigned flags, struct lock_class_key *key) { struct trace_buffer *buffer; @@ -1823,6 +1825,7 @@ struct trace_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, buffer->flags = flags; buffer->clock = trace_clock_local; buffer->reader_lock_key = key; + buffer->name = name; init_irq_work(&buffer->irq_work.work, rb_wake_up_waiters); init_waitqueue_head(&buffer->irq_work.waiters); diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 9aebf904ff97..7700ca1be2a5 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -9384,7 +9384,8 @@ allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, int size buf->tr = tr; - buf->buffer = ring_buffer_alloc(size, rb_flags); + buf->buffer = ring_buffer_alloc(tr->name ? tr->name : "global_trace", + size, rb_flags); if (!buf->buffer) return -ENOMEM; @@ -9421,7 +9422,7 @@ static int allocate_trace_buffers(struct trace_array *tr, int size) return ret; #ifdef CONFIG_TRACER_MAX_TRACE - ret = allocate_trace_buffer(tr, &tr->max_buffer, + ret = allocate_trace_buffer(NULL, &tr->max_buffer, allocate_snapshot ? size : 1); if (MEM_FAIL(ret, "Failed to allocate trace buffer\n")) { free_trace_buffer(&tr->array_buffer); @@ -10473,7 +10474,7 @@ __init static int tracer_alloc_buffers(void) goto out_free_cpumask; /* Used for event triggers */ ret = -ENOMEM; - temp_buffer = ring_buffer_alloc(PAGE_SIZE, RB_FL_OVERWRITE); + temp_buffer = ring_buffer_alloc("temp_buffer", PAGE_SIZE, RB_FL_OVERWRITE); if (!temp_buffer) goto out_rm_hp_state;