From patchwork Fri Sep 24 03:35:48 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 12513935 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3140C433F5 for ; Fri, 24 Sep 2021 03:37:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C313961242 for ; Fri, 24 Sep 2021 03:37:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244035AbhIXDik (ORCPT ); Thu, 23 Sep 2021 23:38:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:36016 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244030AbhIXDik (ORCPT ); Thu, 23 Sep 2021 23:38:40 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 81F3160EFF; Fri, 24 Sep 2021 03:37:07 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.94.2) (envelope-from ) id 1mTc1K-003Hzj-GS; Thu, 23 Sep 2021 23:37:06 -0400 Message-ID: <20210924033706.331234889@goodmis.org> User-Agent: quilt/0.66 Date: Thu, 23 Sep 2021 23:35:48 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Masami Hiramatsu , Mathieu Desnoyers , linux-trace-devel@vger.kernel.org Subject: [PATCH 1/2] tracing: Place trace_pid_list logic into abstract functions References: <20210924033547.939554938@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org From: "Steven Rostedt (VMware)" Instead of having the logic that does trace_pid_list open coded, wrap it in abstract functions. This will allow a rewrite of the logic that implements the trace_pid_list without affecting the users. Note, this causes a change in behavior. Every time a pid is written into the set_*_pid file, it creates a new list and uses RCU to update it. If pid_max is lowered, but there was a pid currently in the list that was higher than pid_max, those pids will now be removed on updating the list. The old behavior kept that from happening. The rewrite of the pid_list logic will no longer depend on pid_max, and will return the old behavior. Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/Makefile | 1 + kernel/trace/ftrace.c | 6 +- kernel/trace/pid_list.c | 165 ++++++++++++++++++++++++++++++++++++ kernel/trace/trace.c | 78 ++++++----------- kernel/trace/trace.h | 14 ++- kernel/trace/trace_events.c | 6 +- 6 files changed, 209 insertions(+), 61 deletions(-) create mode 100644 kernel/trace/pid_list.c diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 6de5d4d63165..bedc5caceec7 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -47,6 +47,7 @@ obj-$(CONFIG_TRACING) += trace_output.o obj-$(CONFIG_TRACING) += trace_seq.o obj-$(CONFIG_TRACING) += trace_stat.o obj-$(CONFIG_TRACING) += trace_printk.o +obj-$(CONFIG_TRACING) += pid_list.o obj-$(CONFIG_TRACING_MAP) += tracing_map.o obj-$(CONFIG_PREEMPTIRQ_DELAY_TEST) += preemptirq_delay_test.o obj-$(CONFIG_SYNTH_EVENT_GEN_TEST) += synth_event_gen_test.o diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 7efbc8aaf7f6..3eec6792f115 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -7184,10 +7184,10 @@ static void clear_ftrace_pids(struct trace_array *tr, int type) synchronize_rcu(); if ((type & TRACE_PIDS) && pid_list) - trace_free_pid_list(pid_list); + trace_pid_list_free(pid_list); if ((type & TRACE_NO_PIDS) && no_pid_list) - trace_free_pid_list(no_pid_list); + trace_pid_list_free(no_pid_list); } void ftrace_clear_pids(struct trace_array *tr) @@ -7428,7 +7428,7 @@ pid_write(struct file *filp, const char __user *ubuf, if (filtered_pids) { synchronize_rcu(); - trace_free_pid_list(filtered_pids); + trace_pid_list_free(filtered_pids); } else if (pid_list && !other_pids) { /* Register a probe to set whether to ignore the tracing of a task */ register_trace_sched_switch(ftrace_filter_pid_sched_switch_probe, tr); diff --git a/kernel/trace/pid_list.c b/kernel/trace/pid_list.c new file mode 100644 index 000000000000..b78c80d7f396 --- /dev/null +++ b/kernel/trace/pid_list.c @@ -0,0 +1,165 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2021 VMware Inc, Steven Rostedt + */ +#include +#include +#include "trace.h" + +struct trace_pid_list { + int pid_max; + unsigned long *pids; +}; + +/** + * trace_pid_list_is_set - test if the pid is set in the list + * @pid_list: The pid list to test + * @pid: The pid to to see if set in the list. + * + * Tests if @pid is is set in the @pid_list. This is usually called + * from the scheduler when a task is scheduled. Its pid is checked + * if it should be traced or not. + * + * Return true if the pid is in the list, false otherwise. + */ +bool trace_pid_list_is_set(struct trace_pid_list *pid_list, unsigned int pid) +{ + /* + * If pid_max changed after filtered_pids was created, we + * by default ignore all pids greater than the previous pid_max. + */ + if (pid >= pid_list->pid_max) + return false; + + return test_bit(pid, pid_list->pids); +} + +/** + * trace_pid_list_set - add a pid to the list + * @pid_list: The pid list to add the @pid to. + * @pid: The pid to add. + * + * Adds @pid to @pid_list. This is usually done explicitly by a user + * adding a task to be traced, or indirectly by the fork function + * when children should be traced and a task's pid is in the list. + * + * Return 0 on success, negative otherwise. + */ +int trace_pid_list_set(struct trace_pid_list *pid_list, unsigned int pid) +{ + /* Sorry, but we don't support pid_max changing after setting */ + if (pid >= pid_list->pid_max) + return -EINVAL; + + set_bit(pid, pid_list->pids); + + return 0; +} + +/** + * trace_pid_list_clear - remove a pid from the list + * @pid_list: The pid list to remove the @pid from. + * @pid: The pid to remove. + * + * Removes @pid from @pid_list. This is usually done explicitly by a user + * removing tasks from tracing, or indirectly by the exit function + * when a task that is set to be traced exits. + * + * Return 0 on success, negative otherwise. + */ +int trace_pid_list_clear(struct trace_pid_list *pid_list, unsigned int pid) +{ + /* Sorry, but we don't support pid_max changing after setting */ + if (pid >= pid_list->pid_max) + return -EINVAL; + + clear_bit(pid, pid_list->pids); + + return 0; +} + +/** + * trace_pid_list_next - return the next pid in the list + * @pid_list: The pid list to examine. + * @pid: The pid to start from + * @next: The pointer to place the pid that is set starting from @pid. + * + * Looks for the next consecutive pid that is in @pid_list starting + * at the pid specified by @pid. If one is set (including @pid), then + * that pid is placed into @next. + * + * Return 0 when a pid is found, -1 if there are no more pids included. + */ +int trace_pid_list_next(struct trace_pid_list *pid_list, unsigned int pid, + unsigned int *next) +{ + pid = find_next_bit(pid_list->pids, pid_list->pid_max, pid); + + if (pid < pid_list->pid_max) { + *next = pid; + return 0; + } + return -1; +} + +/** + * trace_pid_list_first - return the first pid in the list + * @pid_list: The pid list to examine. + * @pid: The pointer to place the pid first found pid that is set. + * + * Looks for the first pid that is set in @pid_list, and places it + * into @pid if found. + * + * Return 0 when a pid is found, -1 if there are no pids set. + */ +int trace_pid_list_first(struct trace_pid_list *pid_list, unsigned int *pid) +{ + unsigned int first; + + first = find_first_bit(pid_list->pids, pid_list->pid_max); + + if (first < pid_list->pid_max) { + *pid = first; + return 0; + } + return -1; +} + +/** + * trace_pid_list_alloc - create a new pid_list + * + * Allocates a new pid_list to store pids into. + * + * Returns the pid_list on success, NULL otherwise. + */ +struct trace_pid_list *trace_pid_list_alloc(void) +{ + struct trace_pid_list *pid_list; + + pid_list = kmalloc(sizeof(*pid_list), GFP_KERNEL); + if (!pid_list) + return NULL; + + pid_list->pid_max = READ_ONCE(pid_max); + + pid_list->pids = vzalloc((pid_list->pid_max + 7) >> 3); + if (!pid_list->pids) { + kfree(pid_list); + return NULL; + } + return pid_list; +} + +/** + * trace_pid_list_free - Frees an allocated pid_list. + * + * Frees the memory for a pid_list that was allocated. + */ +void trace_pid_list_free(struct trace_pid_list *pid_list) +{ + if (!pid_list) + return; + + vfree(pid_list->pids); + kfree(pid_list); +} diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 7896d30d90f7..dcced07a45e6 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -512,12 +512,6 @@ int call_filter_check_discard(struct trace_event_call *call, void *rec, return 0; } -void trace_free_pid_list(struct trace_pid_list *pid_list) -{ - vfree(pid_list->pids); - kfree(pid_list); -} - /** * trace_find_filtered_pid - check if a pid exists in a filtered_pid list * @filtered_pids: The list of pids to check @@ -528,14 +522,7 @@ void trace_free_pid_list(struct trace_pid_list *pid_list) bool trace_find_filtered_pid(struct trace_pid_list *filtered_pids, pid_t search_pid) { - /* - * If pid_max changed after filtered_pids was created, we - * by default ignore all pids greater than the previous pid_max. - */ - if (search_pid >= filtered_pids->pid_max) - return false; - - return test_bit(search_pid, filtered_pids->pids); + return trace_pid_list_is_set(filtered_pids, search_pid); } /** @@ -592,15 +579,11 @@ void trace_filter_add_remove_task(struct trace_pid_list *pid_list, return; } - /* Sorry, but we don't support pid_max changing after setting */ - if (task->pid >= pid_list->pid_max) - return; - /* "self" is set for forks, and NULL for exits */ if (self) - set_bit(task->pid, pid_list->pids); + trace_pid_list_set(pid_list, task->pid); else - clear_bit(task->pid, pid_list->pids); + trace_pid_list_clear(pid_list, task->pid); } /** @@ -617,18 +600,19 @@ void trace_filter_add_remove_task(struct trace_pid_list *pid_list, */ void *trace_pid_next(struct trace_pid_list *pid_list, void *v, loff_t *pos) { - unsigned long pid = (unsigned long)v; + long pid = (unsigned long)v; + unsigned int next; (*pos)++; /* pid already is +1 of the actual previous bit */ - pid = find_next_bit(pid_list->pids, pid_list->pid_max, pid); + if (trace_pid_list_next(pid_list, pid, &next) < 0) + return NULL; - /* Return pid + 1 to allow zero to be represented */ - if (pid < pid_list->pid_max) - return (void *)(pid + 1); + pid = next; - return NULL; + /* Return pid + 1 to allow zero to be represented */ + return (void *)(pid + 1); } /** @@ -645,12 +629,14 @@ void *trace_pid_next(struct trace_pid_list *pid_list, void *v, loff_t *pos) void *trace_pid_start(struct trace_pid_list *pid_list, loff_t *pos) { unsigned long pid; + unsigned int first; loff_t l = 0; - pid = find_first_bit(pid_list->pids, pid_list->pid_max); - if (pid >= pid_list->pid_max) + if (trace_pid_list_first(pid_list, &first) < 0) return NULL; + pid = first; + /* Return pid + 1 so that zero can be the exit value */ for (pid++; pid && l < *pos; pid = (unsigned long)trace_pid_next(pid_list, (void *)pid, &l)) @@ -686,7 +672,7 @@ int trace_pid_write(struct trace_pid_list *filtered_pids, unsigned long val; int nr_pids = 0; ssize_t read = 0; - ssize_t ret = 0; + ssize_t ret; loff_t pos; pid_t pid; @@ -699,34 +685,23 @@ int trace_pid_write(struct trace_pid_list *filtered_pids, * the user. If the operation fails, then the current list is * not modified. */ - pid_list = kmalloc(sizeof(*pid_list), GFP_KERNEL); + pid_list = trace_pid_list_alloc(); if (!pid_list) { trace_parser_put(&parser); return -ENOMEM; } - pid_list->pid_max = READ_ONCE(pid_max); - - /* Only truncating will shrink pid_max */ - if (filtered_pids && filtered_pids->pid_max > pid_list->pid_max) - pid_list->pid_max = filtered_pids->pid_max; - - pid_list->pids = vzalloc((pid_list->pid_max + 7) >> 3); - if (!pid_list->pids) { - trace_parser_put(&parser); - kfree(pid_list); - return -ENOMEM; - } - if (filtered_pids) { /* copy the current bits to the new max */ - for_each_set_bit(pid, filtered_pids->pids, - filtered_pids->pid_max) { - set_bit(pid, pid_list->pids); + ret = trace_pid_list_first(filtered_pids, &pid); + while (!ret) { + trace_pid_list_set(pid_list, pid); + ret = trace_pid_list_next(filtered_pids, pid + 1, &pid); nr_pids++; } } + ret = 0; while (cnt > 0) { pos = 0; @@ -742,12 +717,13 @@ int trace_pid_write(struct trace_pid_list *filtered_pids, ret = -EINVAL; if (kstrtoul(parser.buffer, 0, &val)) break; - if (val >= pid_list->pid_max) - break; pid = (pid_t)val; - set_bit(pid, pid_list->pids); + if (trace_pid_list_set(pid_list, pid) < 0) { + ret = -1; + break; + } nr_pids++; trace_parser_clear(&parser); @@ -756,13 +732,13 @@ int trace_pid_write(struct trace_pid_list *filtered_pids, trace_parser_put(&parser); if (ret < 0) { - trace_free_pid_list(pid_list); + trace_pid_list_free(pid_list); return ret; } if (!nr_pids) { /* Cleared the list of pids */ - trace_free_pid_list(pid_list); + trace_pid_list_free(pid_list); read = ret; pid_list = NULL; } diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index b7c0f8e160fb..fe13a0542486 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -188,10 +188,16 @@ struct trace_options { struct trace_option_dentry *topts; }; -struct trace_pid_list { - int pid_max; - unsigned long *pids; -}; +struct trace_pid_list; + +struct trace_pid_list *trace_pid_list_alloc(void); +void trace_pid_list_free(struct trace_pid_list *pid_list); +bool trace_pid_list_is_set(struct trace_pid_list *pid_list, unsigned int pid); +int trace_pid_list_set(struct trace_pid_list *pid_list, unsigned int pid); +int trace_pid_list_clear(struct trace_pid_list *pid_list, unsigned int pid); +int trace_pid_list_first(struct trace_pid_list *pid_list, unsigned int *pid); +int trace_pid_list_next(struct trace_pid_list *pid_list, unsigned int pid, + unsigned int *next); enum { TRACE_PIDS = BIT(0), diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 830b3b9940f4..bf54d2803261 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -885,10 +885,10 @@ static void __ftrace_clear_event_pids(struct trace_array *tr, int type) tracepoint_synchronize_unregister(); if ((type & TRACE_PIDS) && pid_list) - trace_free_pid_list(pid_list); + trace_pid_list_free(pid_list); if ((type & TRACE_NO_PIDS) && no_pid_list) - trace_free_pid_list(no_pid_list); + trace_pid_list_free(no_pid_list); } static void ftrace_clear_event_pids(struct trace_array *tr, int type) @@ -1967,7 +1967,7 @@ event_pid_write(struct file *filp, const char __user *ubuf, if (filtered_pids) { tracepoint_synchronize_unregister(); - trace_free_pid_list(filtered_pids); + trace_pid_list_free(filtered_pids); } else if (pid_list && !other_pids) { register_pid_events(tr); } From patchwork Fri Sep 24 03:35:49 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 12513937 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 42DD1C4332F for ; Fri, 24 Sep 2021 03:37:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 26B3A61242 for ; Fri, 24 Sep 2021 03:37:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244038AbhIXDik (ORCPT ); Thu, 23 Sep 2021 23:38:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:36028 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244031AbhIXDik (ORCPT ); Thu, 23 Sep 2021 23:38:40 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A6BED61241; Fri, 24 Sep 2021 03:37:07 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.94.2) (envelope-from ) id 1mTc1K-003I0H-Np; Thu, 23 Sep 2021 23:37:06 -0400 Message-ID: <20210924033706.539296792@goodmis.org> User-Agent: quilt/0.66 Date: Thu, 23 Sep 2021 23:35:49 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Masami Hiramatsu , Mathieu Desnoyers , linux-trace-devel@vger.kernel.org Subject: [PATCH 2/2] tracing: Create a sparse bitmask for pid filtering References: <20210924033547.939554938@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org From: "Steven Rostedt (VMware)" When the trace_pid_list was created, the default pid max was 32768. Creating a bitmask that can hold one bit for all 32768 took up 4096 (one page). Having a one page bitmask was not much of a problem, and that was used for mapping pids. But today, systems are bigger and can run more tasks, and now the default pid_max is usually set to 4194304. Which means to handle that many pids requires 524288 bytes. Worse yet, the pid_max can be set to 2^30 (1073741824 or 1G) which would take 134217728 (128M) of memory to store this array. Since the pid_list array is very sparsely populated, it is a huge waste of memory to store all possible bits for each pid when most will not be set. Instead, use a page table scheme to store the array, and allow this to handle up to 32 bit pids. The pid_mask will start out with 1024 entries for the first 10 MSB bits. This will cost 4K for 32 bit architectures and 8K for 64 bit. Each of these will have a 1024 array to store the next 10 bits of the pid (another 4 or 8K). These will hold an 512 byte bitmask (which will cover the LSB 12 bits or 4096 bits). When the trace_pid_list is allocated, it will have the 4/8K upper bits allocated, and then it will allocate a cache for the next upper chunks and the lower chunks (default 6 of each). Then when a bit is "set", these chunks will be pulled from the free list and added to the array. If the free list gets down to a lever (default 2), it will trigger an irqwork that will refill the cache back up. On clearing a bit, if the clear causes the bitmask to be zero, that chunk will then be placed back into the free cache for later use, keeping the need to allocate more down to a minimum. Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/pid_list.c | 460 ++++++++++++++++++++++++++++++++++++---- 1 file changed, 423 insertions(+), 37 deletions(-) diff --git a/kernel/trace/pid_list.c b/kernel/trace/pid_list.c index b78c80d7f396..f307de267a9e 100644 --- a/kernel/trace/pid_list.c +++ b/kernel/trace/pid_list.c @@ -2,15 +2,182 @@ /* * Copyright (C) 2021 VMware Inc, Steven Rostedt */ -#include +#include +#include #include -#include "trace.h" + +/* + * In order to keep track of what pids to trace, a tree is created much + * like page tables are used. This creates a sparse bit map, where + * the tree is filled in when needed. A PID is 32 bits, and is broken + * up into 3 sections based on the bit map of the bits. The 10 MSB + * is the "upper1" section. The next 10 MSB is the "upper2" section + * and the 12 LSB is the "lower" section. + * + * A trace_pid_list structure holds the "upper1" section, in an + * array of 1024 pointers to "upper_chunk" unions, where each has an + * array of 1024 pointers to the "lower_chunk" structures, where each + * has an array of size 512 bytes representing a bitmask of the 12 LSB of + * the PID (512 * 8 = 4096) + * + * When a trace_pid_list is allocated, it includes the 1024 array + * of the upper1 unions. Then a "cache" of upper and lower is allocated + * where these will be assigned as needed. + * + * When a bit is set in the pid_list bitmask, the pid to use has + * the 10 MSB masked, and this is used to index the array in the + * pid_list to find the next upper union. If the element is NULL, + * then one is retrieved from the upper_list cache. If none is + * available, then -ENOMEM is returned. + * + * The next 10 MSB is used to index into the "upper2" section. If this + * element is NULL, then it is retrieved from the lower_list cache. + * Again, if one is not available -ENOMEM is returned. + * + * Finally the 12 LSB of the PID is used to set the bit in the 4096 + * bitmask (made up of 512 bytes). + * + * The upper mask is never freed until the trace_pid_list is freed, + * but the lower sections are moved back to the cache list when + * all the bits are cleared and can be reused. + */ + +#define UPPER1_SIZE 1024 +#define UPPER2_SIZE 1024 + +#define LOWER_BITS 4096 +#define LOWER_SIZE (LOWER_BITS / BITS_PER_LONG) + +#define UPPER1_SHIFT 24 +#define UPPER2_SHIFT 12 +#define LOWER_MASK ((1 << UPPER2_SHIFT) - 1) + +/* UPPER_MASK is 10 bits, done after the shift */ +#define UPPER_MASK ((1 << 10) - 1) + +/* Just keep 6 chunks of both upper and lower in the cache on alloc */ +#define CHUNK_ALLOC 6 + +/* Have 2 chunks free, trigger a refill of the cache */ +#define CHUNK_REALLOC 2 + +union lower_chunk { + union lower_chunk *next; + unsigned long data[LOWER_SIZE]; // 512B in size +}; + +union upper_chunk { + union upper_chunk *next; + union lower_chunk *data[UPPER2_SIZE]; // 4 or 8K in size +}; struct trace_pid_list { - int pid_max; - unsigned long *pids; + raw_spinlock_t lock; + struct irq_work refill_irqwork; + union upper_chunk *upper[UPPER1_SIZE]; // 4 or 8K in size + union upper_chunk *upper_list; + union lower_chunk *lower_list; + int free_upper_chunks; + int free_lower_chunks; }; +static inline union lower_chunk *get_lower_chunk(struct trace_pid_list *pid_list) +{ + union lower_chunk *chunk; + + lockdep_assert_held(&pid_list->lock); + + if (!pid_list->lower_list) + return NULL; + + chunk = pid_list->lower_list; + pid_list->lower_list = chunk->next; + pid_list->free_lower_chunks--; + WARN_ON_ONCE(pid_list->free_lower_chunks < 0); + chunk->next = NULL; + /* + * If a refill needs to happen, it can not happen here + * as the scheduler run queue locks are held. + */ + if (pid_list->free_lower_chunks <= CHUNK_REALLOC) + irq_work_queue(&pid_list->refill_irqwork); + + return chunk; +} + +static inline union upper_chunk *get_upper_chunk(struct trace_pid_list *pid_list) +{ + union upper_chunk *chunk; + + lockdep_assert_held(&pid_list->lock); + + if (!pid_list->upper_list) + return NULL; + + chunk = pid_list->upper_list; + pid_list->upper_list = chunk->next; + pid_list->free_upper_chunks--; + WARN_ON_ONCE(pid_list->free_upper_chunks < 0); + chunk->next = NULL; + /* + * If a refill needs to happen, it can not happen here + * as the scheduler run queue locks are held. + */ + if (pid_list->free_upper_chunks <= CHUNK_REALLOC) + irq_work_queue(&pid_list->refill_irqwork); + + return chunk; +} + +static inline void put_lower_chunk(struct trace_pid_list *pid_list, + union lower_chunk *chunk) +{ + lockdep_assert_held(&pid_list->lock); + + chunk->next = pid_list->lower_list; + pid_list->lower_list = chunk; + pid_list->free_lower_chunks++; +} + +static inline void put_upper_chunk(struct trace_pid_list *pid_list, + union upper_chunk *chunk) +{ + lockdep_assert_held(&pid_list->lock); + + chunk->next = pid_list->upper_list; + pid_list->upper_list = chunk; + pid_list->free_upper_chunks++; +} + +static inline bool upper_empty(union upper_chunk *chunk) +{ + /* + * If chunk->data has no lower chunks, it will be the same + * as a zeroed bitmask. Use find_first_bit() to test it + * and if it doesn't find any bits set, then the array + * is empty. + */ + int bit = find_first_bit((unsigned long *)chunk->data, + sizeof(chunk->data) * 8); + return bit >= sizeof(chunk->data) * 8; +} + +static inline void pid_split(unsigned int pid, unsigned int *upper1, + unsigned int *upper2, unsigned int *lower) +{ + *upper1 = (pid >> UPPER1_SHIFT) & UPPER_MASK; + *upper2 = (pid >> UPPER2_SHIFT) & UPPER_MASK; + *lower = pid & LOWER_MASK; +} + +static inline unsigned int pid_join(unsigned int upper1, + unsigned int upper2, unsigned int lower) +{ + return ((upper1 & UPPER_MASK) << UPPER1_SHIFT) | + ((upper2 & UPPER_MASK) << UPPER2_SHIFT) | + (lower & LOWER_MASK); +} + /** * trace_pid_list_is_set - test if the pid is set in the list * @pid_list: The pid list to test @@ -24,14 +191,29 @@ struct trace_pid_list { */ bool trace_pid_list_is_set(struct trace_pid_list *pid_list, unsigned int pid) { - /* - * If pid_max changed after filtered_pids was created, we - * by default ignore all pids greater than the previous pid_max. - */ - if (pid >= pid_list->pid_max) + union upper_chunk *upper_chunk; + union lower_chunk *lower_chunk; + unsigned long flags; + unsigned int upper1; + unsigned int upper2; + unsigned int lower; + bool ret = false; + + if (!pid_list) return false; - return test_bit(pid, pid_list->pids); + pid_split(pid, &upper1, &upper2, &lower); + + raw_spin_lock_irqsave(&pid_list->lock, flags); + upper_chunk = pid_list->upper[upper1]; + if (upper_chunk) { + lower_chunk = upper_chunk->data[upper2]; + if (lower_chunk) + ret = test_bit(lower, lower_chunk->data); + } + raw_spin_unlock_irqrestore(&pid_list->lock, flags); + + return ret; } /** @@ -47,13 +229,43 @@ bool trace_pid_list_is_set(struct trace_pid_list *pid_list, unsigned int pid) */ int trace_pid_list_set(struct trace_pid_list *pid_list, unsigned int pid) { - /* Sorry, but we don't support pid_max changing after setting */ - if (pid >= pid_list->pid_max) - return -EINVAL; + union upper_chunk *upper_chunk; + union lower_chunk *lower_chunk; + unsigned long flags; + unsigned int upper1; + unsigned int upper2; + unsigned int lower; + int ret; + + if (!pid_list) + return -ENODEV; - set_bit(pid, pid_list->pids); + pid_split(pid, &upper1, &upper2, &lower); - return 0; + raw_spin_lock_irqsave(&pid_list->lock, flags); + upper_chunk = pid_list->upper[upper1]; + if (!upper_chunk) { + upper_chunk = get_upper_chunk(pid_list); + if (!upper_chunk) { + ret = -ENOMEM; + goto out; + } + pid_list->upper[upper1] = upper_chunk; + } + lower_chunk = upper_chunk->data[upper2]; + if (!lower_chunk) { + lower_chunk = get_lower_chunk(pid_list); + if (!lower_chunk) { + ret = -ENOMEM; + goto out; + } + upper_chunk->data[upper2] = lower_chunk; + } + set_bit(lower, lower_chunk->data); + ret = 0; + out: + raw_spin_unlock_irqrestore(&pid_list->lock, flags); + return ret; } /** @@ -69,12 +281,40 @@ int trace_pid_list_set(struct trace_pid_list *pid_list, unsigned int pid) */ int trace_pid_list_clear(struct trace_pid_list *pid_list, unsigned int pid) { - /* Sorry, but we don't support pid_max changing after setting */ - if (pid >= pid_list->pid_max) - return -EINVAL; + union upper_chunk *upper_chunk; + union lower_chunk *lower_chunk; + unsigned long flags; + unsigned int upper1; + unsigned int upper2; + unsigned int lower; + + if (!pid_list) + return -ENODEV; + + pid_split(pid, &upper1, &upper2, &lower); + + raw_spin_lock_irqsave(&pid_list->lock, flags); + upper_chunk = pid_list->upper[upper1]; + if (!upper_chunk) + goto out; + + lower_chunk = upper_chunk->data[upper2]; + if (!lower_chunk) + goto out; - clear_bit(pid, pid_list->pids); + clear_bit(lower, lower_chunk->data); + /* if there's no more bits set, add it to the free list */ + if (find_first_bit(lower_chunk->data, LOWER_BITS) >= LOWER_BITS) { + put_lower_chunk(pid_list, lower_chunk); + upper_chunk->data[upper2] = NULL; + if (upper_empty(upper_chunk)) { + put_upper_chunk(pid_list, upper_chunk); + pid_list->upper[upper1] = NULL; + } + } + out: + raw_spin_unlock_irqrestore(&pid_list->lock, flags); return 0; } @@ -93,13 +333,44 @@ int trace_pid_list_clear(struct trace_pid_list *pid_list, unsigned int pid) int trace_pid_list_next(struct trace_pid_list *pid_list, unsigned int pid, unsigned int *next) { - pid = find_next_bit(pid_list->pids, pid_list->pid_max, pid); + union upper_chunk *upper_chunk; + union lower_chunk *lower_chunk; + unsigned long flags; + unsigned int upper1; + unsigned int upper2; + unsigned int lower; + + if (!pid_list) + return -ENODEV; + + pid_split(pid, &upper1, &upper2, &lower); - if (pid < pid_list->pid_max) { - *next = pid; - return 0; + raw_spin_lock_irqsave(&pid_list->lock, flags); + for (; upper1 <= UPPER_MASK; upper1++, upper2 = 0) { + upper_chunk = pid_list->upper[upper1]; + + if (!upper_chunk) + continue; + + for (; upper2 <= UPPER_MASK; upper2++, lower = 0) { + lower_chunk = upper_chunk->data[upper2]; + if (!lower_chunk) + continue; + + lower = find_next_bit(lower_chunk->data, LOWER_BITS, + lower); + if (lower < LOWER_BITS) + goto found; + } } - return -1; + + found: + raw_spin_unlock_irqrestore(&pid_list->lock, flags); + if (upper1 > UPPER_MASK) + return -1; + + *next = pid_join(upper1, upper2, lower); + return 0; } /** @@ -114,15 +385,79 @@ int trace_pid_list_next(struct trace_pid_list *pid_list, unsigned int pid, */ int trace_pid_list_first(struct trace_pid_list *pid_list, unsigned int *pid) { - unsigned int first; + return trace_pid_list_next(pid_list, 0, pid); +} - first = find_first_bit(pid_list->pids, pid_list->pid_max); +static void pid_list_refill_irq(struct irq_work *iwork) +{ + struct trace_pid_list *pid_list = container_of(iwork, struct trace_pid_list, + refill_irqwork); + union upper_chunk *upper; + union lower_chunk *lower; + union upper_chunk **upper_next = &upper; + union lower_chunk **lower_next = &lower; + int upper_count; + int lower_count; + int ucnt = 0; + int lcnt = 0; + + again: + raw_spin_lock(&pid_list->lock); + upper_count = CHUNK_ALLOC - pid_list->free_upper_chunks; + lower_count = CHUNK_ALLOC - pid_list->free_lower_chunks; + raw_spin_unlock(&pid_list->lock); + + if (upper_count <= 0 && lower_count <= 0) + return; - if (first < pid_list->pid_max) { - *pid = first; - return 0; + while (upper_count-- > 0) { + union upper_chunk *chunk; + + chunk = kzalloc(sizeof(*chunk), GFP_KERNEL); + if (!chunk) + break; + *upper_next = chunk; + upper_next = &chunk->next; + ucnt++; + } + + while (lower_count-- > 0) { + union lower_chunk *chunk; + + chunk = kzalloc(sizeof(*chunk), GFP_KERNEL); + if (!chunk) + break; + *lower_next = chunk; + lower_next = &chunk->next; + lcnt++; } - return -1; + + raw_spin_lock(&pid_list->lock); + if (upper) { + *upper_next = pid_list->upper_list; + pid_list->upper_list = upper; + pid_list->free_upper_chunks += ucnt; + } + if (lower) { + *lower_next = pid_list->lower_list; + pid_list->lower_list = lower; + pid_list->free_lower_chunks += lcnt; + } + raw_spin_unlock(&pid_list->lock); + + /* + * On success of allocating all the chunks, both counters + * will be less than zero. If they are not, then an allocation + * failed, and we should not try again. + */ + if (upper_count >= 0 || lower_count >= 0) + return; + /* + * When the locks were released, free chunks could have + * been used and allocation needs to be done again. Might as + * well allocate it now. + */ + goto again; } /** @@ -135,18 +470,38 @@ int trace_pid_list_first(struct trace_pid_list *pid_list, unsigned int *pid) struct trace_pid_list *trace_pid_list_alloc(void) { struct trace_pid_list *pid_list; + int i; - pid_list = kmalloc(sizeof(*pid_list), GFP_KERNEL); + pid_list = kzalloc(sizeof(*pid_list), GFP_KERNEL); if (!pid_list) return NULL; - pid_list->pid_max = READ_ONCE(pid_max); + init_irq_work(&pid_list->refill_irqwork, pid_list_refill_irq); - pid_list->pids = vzalloc((pid_list->pid_max + 7) >> 3); - if (!pid_list->pids) { - kfree(pid_list); - return NULL; + raw_spin_lock_init(&pid_list->lock); + + for (i = 0; i < CHUNK_ALLOC; i++) { + union upper_chunk *chunk; + + chunk = kzalloc(sizeof(*chunk), GFP_KERNEL); + if (!chunk) + break; + chunk->next = pid_list->upper_list; + pid_list->upper_list = chunk; + pid_list->free_upper_chunks++; + } + + for (i = 0; i < CHUNK_ALLOC; i++) { + union lower_chunk *chunk; + + chunk = kzalloc(sizeof(*chunk), GFP_KERNEL); + if (!chunk) + break; + chunk->next = pid_list->lower_list; + pid_list->lower_list = chunk; + pid_list->free_lower_chunks++; } + return pid_list; } @@ -157,9 +512,40 @@ struct trace_pid_list *trace_pid_list_alloc(void) */ void trace_pid_list_free(struct trace_pid_list *pid_list) { + union upper_chunk *upper; + union lower_chunk *lower; + int i, j; + if (!pid_list) return; - vfree(pid_list->pids); + irq_work_sync(&pid_list->refill_irqwork); + + while (pid_list->lower_list) { + union lower_chunk *chunk; + + chunk = pid_list->lower_list; + pid_list->lower_list = pid_list->lower_list->next; + kfree(chunk); + } + + while (pid_list->upper_list) { + union upper_chunk *chunk; + + chunk = pid_list->upper_list; + pid_list->upper_list = pid_list->upper_list->next; + kfree(chunk); + } + + for (i = 0; i < UPPER1_SIZE; i++) { + upper = pid_list->upper[i]; + if (upper) { + for (j = 0; j < UPPER2_SIZE; j++) { + lower = upper->data[j]; + kfree(lower); + } + kfree(upper); + } + } kfree(pid_list); }