Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936581Ab3DHKV6 (ORCPT ); Mon, 8 Apr 2013 06:21:58 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:42665 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935400Ab3DHJv0 (ORCPT ); Mon, 8 Apr 2013 05:51:26 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Steven Rostedt , Lingzhu Xiang , Luis Henriques Subject: [PATCH 018/102] tracing: Prevent buffer overwrite disabled for latency tracers Date: Mon, 8 Apr 2013 10:49:33 +0100 Message-Id: <1365414657-29191-19-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1365414657-29191-1-git-send-email-luis.henriques@canonical.com> References: <1365414657-29191-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9621 Lines: 300 3.5.7.10 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Lingzhu Xiang commit 613f04a0f51e6e68ac6fe571ab79da3c0a5eb4da upstream. Backported for 3.4-stable. Re-added current_trace NULL checks; removed allocated_snapshot field; adapted to tracing_trace_options_write without trace_set_options. From: "Steven Rostedt (Red Hat)" The latency tracers require the buffers to be in overwrite mode, otherwise they get screwed up. Force the buffers to stay in overwrite mode when latency tracers are enabled. Added a flag_changed() method to the tracer structure to allow the tracers to see what flags are being changed, and also be able to prevent the change from happing. Cc: stable@vger.kernel.org Signed-off-by: Steven Rostedt Signed-off-by: Lingzhu Xiang Reviewed-by: CAI Qian [ luis: adjust context ] Signed-off-by: Luis Henriques --- kernel/trace/trace.c | 35 +++++++++++++++++++++++++++++------ kernel/trace/trace.h | 7 +++++++ kernel/trace/trace_irqsoff.c | 19 ++++++++++++++----- kernel/trace/trace_sched_wakeup.c | 18 +++++++++++++----- 4 files changed, 63 insertions(+), 16 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b354405..34c61b2 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2762,11 +2762,25 @@ static int set_tracer_option(struct tracer *trace, char *cmp, int neg) return -EINVAL; } -static void set_tracer_flags(unsigned int mask, int enabled) +/* Some tracers require overwrite to stay enabled */ +int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set) +{ + if (tracer->enabled && (mask & TRACE_ITER_OVERWRITE) && !set) + return -1; + + return 0; +} + +int set_tracer_flag(unsigned int mask, int enabled) { /* do nothing if flag is already set */ if (!!(trace_flags & mask) == !!enabled) - return; + return 0; + + /* Give the tracer a chance to approve the change */ + if (current_trace->flag_changed) + if (current_trace->flag_changed(current_trace, mask, !!enabled)) + return -EINVAL; if (enabled) trace_flags |= mask; @@ -2782,6 +2796,8 @@ static void set_tracer_flags(unsigned int mask, int enabled) ring_buffer_change_overwrite(max_tr.buffer, enabled); #endif } + + return 0; } static ssize_t @@ -2791,7 +2807,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf, char buf[64]; char *cmp; int neg = 0; - int ret = 0; + int ret = -ENODEV; int i; if (cnt >= sizeof(buf)) @@ -2812,7 +2828,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf, for (i = 0; trace_options[i]; i++) { if (strcmp(cmp, trace_options[i]) == 0) { - set_tracer_flags(1 << i, !neg); + ret = set_tracer_flag(1 << i, !neg); break; } } @@ -2823,7 +2839,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf, mutex_unlock(&trace_types_lock); - if (ret) + if (ret < 0) return ret; *ppos += cnt; @@ -3166,6 +3182,9 @@ static int tracing_set_tracer(const char *buf) goto out; trace_branch_disable(); + + current_trace->enabled = false; + if (current_trace && current_trace->reset) current_trace->reset(tr); if (current_trace && current_trace->use_max_tr) { @@ -3202,6 +3221,7 @@ static int tracing_set_tracer(const char *buf) goto out; } + current_trace->enabled = true; trace_branch_enable(tr); out: mutex_unlock(&trace_types_lock); @@ -4605,9 +4625,12 @@ trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt, return -EINVAL; mutex_lock(&trace_types_lock); - set_tracer_flags(1 << index, val); + ret = set_tracer_flag(1 << index, val); mutex_unlock(&trace_types_lock); + if (ret < 0) + return ret; + *ppos += cnt; return cnt; diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 5aec220..29812da 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -283,10 +283,14 @@ struct tracer { enum print_line_t (*print_line)(struct trace_iterator *iter); /* If you handled the flag setting, return 0 */ int (*set_flag)(u32 old_flags, u32 bit, int set); + /* Return 0 if OK with change, else return non-zero */ + int (*flag_changed)(struct tracer *tracer, + u32 mask, int set); struct tracer *next; struct tracer_flags *flags; int print_max; int use_max_tr; + bool enabled; }; @@ -833,6 +837,9 @@ extern const char *__stop___trace_bprintk_fmt[]; void trace_printk_init_buffers(void); +int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set); +int set_tracer_flag(unsigned int mask, int enabled); + #undef FTRACE_ENTRY #define FTRACE_ENTRY(call, struct_name, id, tstruct, print, filter) \ extern struct ftrace_event_call \ diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c index 99d20e9..8dd139a 100644 --- a/kernel/trace/trace_irqsoff.c +++ b/kernel/trace/trace_irqsoff.c @@ -32,7 +32,7 @@ enum { static int trace_type __read_mostly; -static int save_lat_flag; +static int save_flags; static void stop_irqsoff_tracer(struct trace_array *tr, int graph); static int start_irqsoff_tracer(struct trace_array *tr, int graph); @@ -557,8 +557,11 @@ static void stop_irqsoff_tracer(struct trace_array *tr, int graph) static void __irqsoff_tracer_init(struct trace_array *tr) { - save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT; - trace_flags |= TRACE_ITER_LATENCY_FMT; + save_flags = trace_flags; + + /* non overwrite screws up the latency tracers */ + set_tracer_flag(TRACE_ITER_OVERWRITE, 1); + set_tracer_flag(TRACE_ITER_LATENCY_FMT, 1); tracing_max_latency = 0; irqsoff_trace = tr; @@ -572,10 +575,13 @@ static void __irqsoff_tracer_init(struct trace_array *tr) static void irqsoff_tracer_reset(struct trace_array *tr) { + int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT; + int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE; + stop_irqsoff_tracer(tr, is_graph()); - if (!save_lat_flag) - trace_flags &= ~TRACE_ITER_LATENCY_FMT; + set_tracer_flag(TRACE_ITER_LATENCY_FMT, lat_flag); + set_tracer_flag(TRACE_ITER_OVERWRITE, overwrite_flag); } static void irqsoff_tracer_start(struct trace_array *tr) @@ -608,6 +614,7 @@ static struct tracer irqsoff_tracer __read_mostly = .print_line = irqsoff_print_line, .flags = &tracer_flags, .set_flag = irqsoff_set_flag, + .flag_changed = trace_keep_overwrite, #ifdef CONFIG_FTRACE_SELFTEST .selftest = trace_selftest_startup_irqsoff, #endif @@ -641,6 +648,7 @@ static struct tracer preemptoff_tracer __read_mostly = .print_line = irqsoff_print_line, .flags = &tracer_flags, .set_flag = irqsoff_set_flag, + .flag_changed = trace_keep_overwrite, #ifdef CONFIG_FTRACE_SELFTEST .selftest = trace_selftest_startup_preemptoff, #endif @@ -676,6 +684,7 @@ static struct tracer preemptirqsoff_tracer __read_mostly = .print_line = irqsoff_print_line, .flags = &tracer_flags, .set_flag = irqsoff_set_flag, + .flag_changed = trace_keep_overwrite, #ifdef CONFIG_FTRACE_SELFTEST .selftest = trace_selftest_startup_preemptirqsoff, #endif diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c index ff791ea..9eadedc 100644 --- a/kernel/trace/trace_sched_wakeup.c +++ b/kernel/trace/trace_sched_wakeup.c @@ -36,7 +36,7 @@ static void __wakeup_reset(struct trace_array *tr); static int wakeup_graph_entry(struct ftrace_graph_ent *trace); static void wakeup_graph_return(struct ftrace_graph_ret *trace); -static int save_lat_flag; +static int save_flags; #define TRACE_DISPLAY_GRAPH 1 @@ -539,8 +539,11 @@ static void stop_wakeup_tracer(struct trace_array *tr) static int __wakeup_tracer_init(struct trace_array *tr) { - save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT; - trace_flags |= TRACE_ITER_LATENCY_FMT; + save_flags = trace_flags; + + /* non overwrite screws up the latency tracers */ + set_tracer_flag(TRACE_ITER_OVERWRITE, 1); + set_tracer_flag(TRACE_ITER_LATENCY_FMT, 1); tracing_max_latency = 0; wakeup_trace = tr; @@ -562,12 +565,15 @@ static int wakeup_rt_tracer_init(struct trace_array *tr) static void wakeup_tracer_reset(struct trace_array *tr) { + int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT; + int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE; + stop_wakeup_tracer(tr); /* make sure we put back any tasks we are tracing */ wakeup_reset(tr); - if (!save_lat_flag) - trace_flags &= ~TRACE_ITER_LATENCY_FMT; + set_tracer_flag(TRACE_ITER_LATENCY_FMT, lat_flag); + set_tracer_flag(TRACE_ITER_OVERWRITE, overwrite_flag); } static void wakeup_tracer_start(struct trace_array *tr) @@ -593,6 +599,7 @@ static struct tracer wakeup_tracer __read_mostly = .print_line = wakeup_print_line, .flags = &tracer_flags, .set_flag = wakeup_set_flag, + .flag_changed = trace_keep_overwrite, #ifdef CONFIG_FTRACE_SELFTEST .selftest = trace_selftest_startup_wakeup, #endif @@ -614,6 +621,7 @@ static struct tracer wakeup_rt_tracer __read_mostly = .print_line = wakeup_print_line, .flags = &tracer_flags, .set_flag = wakeup_set_flag, + .flag_changed = trace_keep_overwrite, #ifdef CONFIG_FTRACE_SELFTEST .selftest = trace_selftest_startup_wakeup, #endif -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/