From patchwork Mon Jan 29 14:27:59 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent Donnefort X-Patchwork-Id: 13535751 Received: from mail-yw1-f201.google.com (mail-yw1-f201.google.com [209.85.128.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4CF4686128 for ; Mon, 29 Jan 2024 14:28:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706538500; cv=none; b=beSi1noWbvH1m9Scl2kYvCS/1fZ0rXvtFZxOsEUMzFmZnRqOVGFIoQj0AfSzT/gWA6gP1iq2UdhgzkDPqvsRiIplPK0qL+nrebahu4NB4uLl3st3ux/s9KwG/BLuMiaSNYW89OnSxwKA9b+ysNVHeF2PzK4arUySh7fE1WoKA4o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706538500; c=relaxed/simple; bh=E6UNj21N9nGf6EXoj+iWwGVYkleK4uyYB0kIXGMO3ko=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=P15LijlXf7urtXGLvfq/ZqX2n4uD+MSjqErpCNHzRhgpwkHAjVyGaSldWoFIchguggvQuO7Xq7ojmthNCtNS3h7jzpkjJpK/euMOelY9jJRllcH2Z3h7xGOtUKYABzm3y/Ho5bVNw9u/QCXBm1PL2mDVrZEZf7YdzuBwYjjvqFo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=0afKLLTx; arc=none smtp.client-ip=209.85.128.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="0afKLLTx" Received: by mail-yw1-f201.google.com with SMTP id 00721157ae682-602d494b68aso42735777b3.2 for ; Mon, 29 Jan 2024 06:28:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1706538497; x=1707143297; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=q7MsjY0/2c9mGaJnQcEyejruJlnIDyMNckUiDR6Tnrs=; b=0afKLLTx1FBLaZ/Q6refGm5kUff6rJ/uW/QKoeqdTf6Uk/rG+QXDiyVUg0v+zFtPKA O3bwBDg5XbpvxAqoHMl+3dhkLRM+fVWpl2Qgj02hOCl/8UNzqEvex60N9kWoi/3yd7IS AOriC3MwSdw3yl1q7KBbMfgWwrBzqQJGo4o/gnz6OswGBgPZceWjvogv54vN0TYFW4tf B/71FpXy2A0h6KmGxTTDlK1qVYK51F9cYZepue/+sdc6T8TV3WG2cIyMWOu8Fn4ZefuD 9LDhB9F6bEZNHC1SOlEfbn0yPQH46OUQVMiZ/HKCgVBC5xu5sYKYVxuYBP9v0R3qKvl6 /45A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706538497; x=1707143297; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=q7MsjY0/2c9mGaJnQcEyejruJlnIDyMNckUiDR6Tnrs=; b=OocgA5/29rCvAuL0FlCVnuKYLjD7SBxvS7f6g4S22HJMMbpbPB2KCESzkGhHboHfFt ZZEcs0DIemgwed6uS/kOtm6IqoI93H3I9lhBiPzP2D1L72rdimpciKTw9P5VTBrr2TXu hPsx27GyWUldfbV28eh276nJgjSJtT8PrjwH8hNnIyWqqrA39Jf9idGl6aje6s7OoI+s sgV62kozR95hRqaR2C4gCen13jzhJPyttcNrHirCEqLi9qw00KSnQASBzbPBIn+T86gG YTQ7wzEH1N42YTlQX6DdWlVM36iDHEOcOdESvDSKvougGPcD+0HSrbfxft+DUL4HzHgC h+EQ== X-Gm-Message-State: AOJu0YzBPltvJvU+8ulb5rgVaWVEaBvoV1JUF+LFLb1KIppmZvUrYvlg 1+a8lL92hUa5T7jKiQD3Uyzw8cRiKe+wfMIFi5sx+3LOuBQoD9crJA/RJdVu4lm+V8B8KQzqF0n Ixu1KCa/aULY0oJIETQ== X-Google-Smtp-Source: AGHT+IFh8xyRibCwbDS89IsRYVO3WeP9Fhcc6x4KC5I4Asw/F6M+w2+sZAcr0wqttwNeJ7ilqXy645GwGpAKqCFS X-Received: from vdonnefort.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:2eea]) (user=vdonnefort job=sendgmr) by 2002:a05:690c:38a:b0:5fb:7b86:db36 with SMTP id bh10-20020a05690c038a00b005fb7b86db36mr1923105ywb.4.1706538497399; Mon, 29 Jan 2024 06:28:17 -0800 (PST) Date: Mon, 29 Jan 2024 14:27:59 +0000 In-Reply-To: <20240129142802.2145305-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240129142802.2145305-1-vdonnefort@google.com> X-Mailer: git-send-email 2.43.0.429.g432eaa2c6b-goog Message-ID: <20240129142802.2145305-4-vdonnefort@google.com> Subject: [PATCH v13 3/6] tracing: Add snapshot refcount From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: mathieu.desnoyers@efficios.com, kernel-team@android.com, Vincent Donnefort When a ring-buffer is memory mapped by user-space, no trace or ring-buffer swap is possible. This means the snapshot feature is mutually exclusive with the memory mapping. Having a refcount on snapshot users will help to know if a mapping is possible or not. Signed-off-by: Vincent Donnefort diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 2a7c6fd934e9..b6a0e506b3f9 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1300,6 +1300,52 @@ static void free_snapshot(struct trace_array *tr) tr->allocated_snapshot = false; } +static int tracing_arm_snapshot_locked(struct trace_array *tr) +{ + int ret; + + lockdep_assert_held(&trace_types_lock); + + if (tr->snapshot == UINT_MAX) + return -EBUSY; + + ret = tracing_alloc_snapshot_instance(tr); + if (ret) + return ret; + + tr->snapshot++; + + return 0; +} + +static void tracing_disarm_snapshot_locked(struct trace_array *tr) +{ + lockdep_assert_held(&trace_types_lock); + + if (WARN_ON(!tr->snapshot)) + return; + + tr->snapshot--; +} + +int tracing_arm_snapshot(struct trace_array *tr) +{ + int ret; + + mutex_lock(&trace_types_lock); + ret = tracing_arm_snapshot_locked(tr); + mutex_unlock(&trace_types_lock); + + return ret; +} + +void tracing_disarm_snapshot(struct trace_array *tr) +{ + mutex_lock(&trace_types_lock); + tracing_disarm_snapshot_locked(tr); + mutex_unlock(&trace_types_lock); +} + /** * tracing_alloc_snapshot - allocate snapshot buffer. * @@ -1373,10 +1419,6 @@ int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, mutex_lock(&trace_types_lock); - ret = tracing_alloc_snapshot_instance(tr); - if (ret) - goto fail_unlock; - if (tr->current_trace->use_max_tr) { ret = -EBUSY; goto fail_unlock; @@ -1395,6 +1437,10 @@ int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, goto fail_unlock; } + ret = tracing_arm_snapshot_locked(tr); + if (ret) + goto fail_unlock; + local_irq_disable(); arch_spin_lock(&tr->max_lock); tr->cond_snapshot = cond_snapshot; @@ -1439,6 +1485,8 @@ int tracing_snapshot_cond_disable(struct trace_array *tr) arch_spin_unlock(&tr->max_lock); local_irq_enable(); + tracing_disarm_snapshot(tr); + return ret; } EXPORT_SYMBOL_GPL(tracing_snapshot_cond_disable); @@ -6593,11 +6641,12 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf) */ synchronize_rcu(); free_snapshot(tr); + tracing_disarm_snapshot_locked(tr); } - if (t->use_max_tr && !tr->allocated_snapshot) { - ret = tracing_alloc_snapshot_instance(tr); - if (ret < 0) + if (t->use_max_tr) { + ret = tracing_arm_snapshot_locked(tr); + if (ret) goto out; } #else @@ -6606,8 +6655,13 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf) if (t->init) { ret = tracer_init(t, tr); - if (ret) + if (ret) { +#ifdef CONFIG_TRACER_MAX_TRACE + if (t->use_max_tr) + tracing_disarm_snapshot_locked(tr); +#endif goto out; + } } tr->current_trace = t; @@ -7709,10 +7763,11 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt, if (tr->allocated_snapshot) ret = resize_buffer_duplicate_size(&tr->max_buffer, &tr->array_buffer, iter->cpu_file); - else - ret = tracing_alloc_snapshot_instance(tr); - if (ret < 0) + + ret = tracing_arm_snapshot_locked(tr); + if (ret) break; + /* Now, we're going to swap */ if (iter->cpu_file == RING_BUFFER_ALL_CPUS) { local_irq_disable(); @@ -7722,6 +7777,7 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt, smp_call_function_single(iter->cpu_file, tracing_swap_cpu_buffer, (void *)tr, 1); } + tracing_disarm_snapshot_locked(tr); break; default: if (tr->allocated_snapshot) { @@ -8846,8 +8902,13 @@ ftrace_trace_snapshot_callback(struct trace_array *tr, struct ftrace_hash *hash, ops = param ? &snapshot_count_probe_ops : &snapshot_probe_ops; - if (glob[0] == '!') - return unregister_ftrace_function_probe_func(glob+1, tr, ops); + if (glob[0] == '!') { + ret = unregister_ftrace_function_probe_func(glob+1, tr, ops); + if (!ret) + tracing_disarm_snapshot(tr); + + return ret; + } if (!param) goto out_reg; @@ -8866,12 +8927,13 @@ ftrace_trace_snapshot_callback(struct trace_array *tr, struct ftrace_hash *hash, return ret; out_reg: - ret = tracing_alloc_snapshot_instance(tr); + ret = tracing_arm_snapshot(tr); if (ret < 0) goto out; ret = register_ftrace_function_probe(glob, tr, ops, count); - + if (ret < 0) + tracing_disarm_snapshot(tr); out: return ret < 0 ? ret : 0; } diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 00f873910c5d..3aa06bd5e48d 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -334,6 +334,7 @@ struct trace_array { */ struct array_buffer max_buffer; bool allocated_snapshot; + unsigned int snapshot; #endif #ifdef CONFIG_TRACER_MAX_TRACE unsigned long max_latency; @@ -1973,12 +1974,16 @@ static inline void trace_event_eval_update(struct trace_eval_map **map, int len) #ifdef CONFIG_TRACER_SNAPSHOT void tracing_snapshot_instance(struct trace_array *tr); int tracing_alloc_snapshot_instance(struct trace_array *tr); +int tracing_arm_snapshot(struct trace_array *tr); +void tracing_disarm_snapshot(struct trace_array *tr); #else static inline void tracing_snapshot_instance(struct trace_array *tr) { } static inline int tracing_alloc_snapshot_instance(struct trace_array *tr) { return 0; } +static inline int tracing_arm_snapshot(struct trace_array *tr) { return 0; } +static inline void tracing_disarm_snapshot(struct trace_array *tr) { } #endif #ifdef CONFIG_PREEMPT_TRACER diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c index b33c3861fbbb..62e4f58b8671 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -597,20 +597,12 @@ static int register_trigger(char *glob, return ret; } -/** - * unregister_trigger - Generic event_command @unreg implementation - * @glob: The raw string used to register the trigger - * @test: Trigger-specific data used to find the trigger to remove - * @file: The trace_event_file associated with the event - * - * Common implementation for event trigger unregistration. - * - * Usually used directly as the @unreg method in event command - * implementations. +/* + * True if the trigger was found and unregistered, else false. */ -static void unregister_trigger(char *glob, - struct event_trigger_data *test, - struct trace_event_file *file) +static bool try_unregister_trigger(char *glob, + struct event_trigger_data *test, + struct trace_event_file *file) { struct event_trigger_data *data = NULL, *iter; @@ -626,8 +618,32 @@ static void unregister_trigger(char *glob, } } - if (data && data->ops->free) - data->ops->free(data); + if (data) { + if (data->ops->free) + data->ops->free(data); + + return true; + } + + return false; +} + +/** + * unregister_trigger - Generic event_command @unreg implementation + * @glob: The raw string used to register the trigger + * @test: Trigger-specific data used to find the trigger to remove + * @file: The trace_event_file associated with the event + * + * Common implementation for event trigger unregistration. + * + * Usually used directly as the @unreg method in event command + * implementations. + */ +static void unregister_trigger(char *glob, + struct event_trigger_data *test, + struct trace_event_file *file) +{ + try_unregister_trigger(glob, test, file); } /* @@ -1470,7 +1486,7 @@ register_snapshot_trigger(char *glob, struct event_trigger_data *data, struct trace_event_file *file) { - int ret = tracing_alloc_snapshot_instance(file->tr); + int ret = tracing_arm_snapshot(file->tr); if (ret < 0) return ret; @@ -1478,6 +1494,14 @@ register_snapshot_trigger(char *glob, return register_trigger(glob, data, file); } +static void unregister_snapshot_trigger(char *glob, + struct event_trigger_data *data, + struct trace_event_file *file) +{ + if (try_unregister_trigger(glob, data, file)) + tracing_disarm_snapshot(file->tr); +} + static int snapshot_trigger_print(struct seq_file *m, struct event_trigger_data *data) { @@ -1510,7 +1534,7 @@ static struct event_command trigger_snapshot_cmd = { .trigger_type = ETT_SNAPSHOT, .parse = event_trigger_parse, .reg = register_snapshot_trigger, - .unreg = unregister_trigger, + .unreg = unregister_snapshot_trigger, .get_trigger_ops = snapshot_get_trigger_ops, .set_filter = set_trigger_filter, };