From cf6ab6d9143b157786bf29bca5c32e55234bb07d Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Mon, 15 Dec 2014 20:13:31 -0500 Subject: tracing: Add ref count to tracer for when they are being read by pipe When one of the trace pipe files are being read (by either the trace_pipe or trace_pipe_raw), do not allow the current_trace to change. By adding a ref count that is incremented when the pipe files are opened, will prevent the current_trace from being changed. This will allow for the removal of the global trace_types_lock from reading the pipe buffers (which is currently a bottle neck). Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 2e767972e99c..ed3fba1d6570 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4140,6 +4140,12 @@ static int tracing_set_tracer(struct trace_array *tr, const char *buf) goto out; } + /* If trace pipe files are being read, we can't change the tracer */ + if (tr->current_trace->ref) { + ret = -EBUSY; + goto out; + } + trace_branch_disable(); tr->current_trace->enabled--; @@ -4363,6 +4369,8 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp) iter->trace->pipe_open(iter); nonseekable_open(inode, filp); + + tr->current_trace->ref++; out: mutex_unlock(&trace_types_lock); return ret; @@ -4382,6 +4390,8 @@ static int tracing_release_pipe(struct inode *inode, struct file *file) mutex_lock(&trace_types_lock); + tr->current_trace->ref--; + if (iter->trace->pipe_close) iter->trace->pipe_close(iter); @@ -5331,6 +5341,8 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp) filp->private_data = info; + tr->current_trace->ref++; + mutex_unlock(&trace_types_lock); ret = nonseekable_open(inode, filp); @@ -5437,6 +5449,8 @@ static int tracing_buffers_release(struct inode *inode, struct file *file) mutex_lock(&trace_types_lock); + iter->tr->current_trace->ref--; + __trace_array_put(iter->tr); if (info->spare) @@ -6416,7 +6430,7 @@ static int instance_delete(const char *name) goto out_unlock; ret = -EBUSY; - if (tr->ref) + if (tr->ref || (tr->current_trace && tr->current_trace->ref)) goto out_unlock; list_del(&tr->list); -- cgit v1.2.2 From d716ff71dd12bc6328f84a9ec1c3647daf01c827 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Mon, 15 Dec 2014 22:31:07 -0500 Subject: tracing: Remove taking of trace_types_lock in pipe files Taking the global mutex "trace_types_lock" in the trace_pipe files causes a bottle neck as most the pipe files can be read per cpu and there's no reason to serialize them. The current_trace variable was given a ref count and it can not change when the ref count is not zero. Opening the trace_pipe files will up the ref count (and decremented on close), so that the lock no longer needs to be taken when accessing the current_trace variable. Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 110 +++++++++++++-------------------------------------- 1 file changed, 28 insertions(+), 82 deletions(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index ed3fba1d6570..7669b1f3234e 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4332,17 +4332,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp) } trace_seq_init(&iter->seq); - - /* - * We make a copy of the current tracer to avoid concurrent - * changes on it while we are reading. - */ - iter->trace = kmalloc(sizeof(*iter->trace), GFP_KERNEL); - if (!iter->trace) { - ret = -ENOMEM; - goto fail; - } - *iter->trace = *tr->current_trace; + iter->trace = tr->current_trace; if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) { ret = -ENOMEM; @@ -4399,7 +4389,6 @@ static int tracing_release_pipe(struct inode *inode, struct file *file) free_cpumask_var(iter->started); mutex_destroy(&iter->mutex); - kfree(iter->trace); kfree(iter); trace_array_put(tr); @@ -4432,7 +4421,7 @@ tracing_poll_pipe(struct file *filp, poll_table *poll_table) return trace_poll(iter, filp, poll_table); } -/* Must be called with trace_types_lock mutex held. */ +/* Must be called with iter->mutex held. */ static int tracing_wait_pipe(struct file *filp) { struct trace_iterator *iter = filp->private_data; @@ -4477,7 +4466,6 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) { struct trace_iterator *iter = filp->private_data; - struct trace_array *tr = iter->tr; ssize_t sret; /* return any leftover data */ @@ -4487,12 +4475,6 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, trace_seq_init(&iter->seq); - /* copy the tracer to avoid using a global lock all around */ - mutex_lock(&trace_types_lock); - if (unlikely(iter->trace->name != tr->current_trace->name)) - *iter->trace = *tr->current_trace; - mutex_unlock(&trace_types_lock); - /* * Avoid more than one consumer on a single file descriptor * This is just a matter of traces coherency, the ring buffer itself @@ -4652,7 +4634,6 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, .ops = &tracing_pipe_buf_ops, .spd_release = tracing_spd_release_pipe, }; - struct trace_array *tr = iter->tr; ssize_t ret; size_t rem; unsigned int i; @@ -4660,12 +4641,6 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, if (splice_grow_spd(pipe, &spd)) return -ENOMEM; - /* copy the tracer to avoid using a global lock all around */ - mutex_lock(&trace_types_lock); - if (unlikely(iter->trace->name != tr->current_trace->name)) - *iter->trace = *tr->current_trace; - mutex_unlock(&trace_types_lock); - mutex_lock(&iter->mutex); if (iter->trace->splice_read) { @@ -5373,21 +5348,16 @@ tracing_buffers_read(struct file *filp, char __user *ubuf, if (!count) return 0; - mutex_lock(&trace_types_lock); - #ifdef CONFIG_TRACER_MAX_TRACE - if (iter->snapshot && iter->tr->current_trace->use_max_tr) { - size = -EBUSY; - goto out_unlock; - } + if (iter->snapshot && iter->tr->current_trace->use_max_tr) + return -EBUSY; #endif if (!info->spare) info->spare = ring_buffer_alloc_read_page(iter->trace_buffer->buffer, iter->cpu_file); - size = -ENOMEM; if (!info->spare) - goto out_unlock; + return -ENOMEM; /* Do we have previous read data to read? */ if (info->read < PAGE_SIZE) @@ -5403,21 +5373,16 @@ tracing_buffers_read(struct file *filp, char __user *ubuf, if (ret < 0) { if (trace_empty(iter)) { - if ((filp->f_flags & O_NONBLOCK)) { - size = -EAGAIN; - goto out_unlock; - } - mutex_unlock(&trace_types_lock); + if ((filp->f_flags & O_NONBLOCK)) + return -EAGAIN; + ret = wait_on_pipe(iter, false); - mutex_lock(&trace_types_lock); - if (ret) { - size = ret; - goto out_unlock; - } + if (ret) + return ret; + goto again; } - size = 0; - goto out_unlock; + return 0; } info->read = 0; @@ -5427,18 +5392,14 @@ tracing_buffers_read(struct file *filp, char __user *ubuf, size = count; ret = copy_to_user(ubuf, info->spare + info->read, size); - if (ret == size) { - size = -EFAULT; - goto out_unlock; - } + if (ret == size) + return -EFAULT; + size -= ret; *ppos += size; info->read += size; - out_unlock: - mutex_unlock(&trace_types_lock); - return size; } @@ -5536,30 +5497,20 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, int entries, size, i; ssize_t ret = 0; - mutex_lock(&trace_types_lock); - #ifdef CONFIG_TRACER_MAX_TRACE - if (iter->snapshot && iter->tr->current_trace->use_max_tr) { - ret = -EBUSY; - goto out; - } + if (iter->snapshot && iter->tr->current_trace->use_max_tr) + return -EBUSY; #endif - if (splice_grow_spd(pipe, &spd)) { - ret = -ENOMEM; - goto out; - } + if (splice_grow_spd(pipe, &spd)) + return -ENOMEM; - if (*ppos & (PAGE_SIZE - 1)) { - ret = -EINVAL; - goto out; - } + if (*ppos & (PAGE_SIZE - 1)) + return -EINVAL; if (len & (PAGE_SIZE - 1)) { - if (len < PAGE_SIZE) { - ret = -EINVAL; - goto out; - } + if (len < PAGE_SIZE) + return -EINVAL; len &= PAGE_MASK; } @@ -5620,25 +5571,20 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, /* did we read anything? */ if (!spd.nr_pages) { if (ret) - goto out; + return ret; + + if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK)) + return -EAGAIN; - if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK)) { - ret = -EAGAIN; - goto out; - } - mutex_unlock(&trace_types_lock); ret = wait_on_pipe(iter, true); - mutex_lock(&trace_types_lock); if (ret) - goto out; + return ret; goto again; } ret = splice_to_pipe(pipe, &spd); splice_shrink_spd(&spd); -out: - mutex_unlock(&trace_types_lock); return ret; } -- cgit v1.2.2 From 14a5ae40f0def33a422a45b2ed09198adb7bf11c Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Tue, 20 Jan 2015 11:14:16 -0500 Subject: tracing: Use IS_ERR() check for return value of tracing_init_dentry() tracing_init_dentry() will soon return NULL as a valid pointer for the top level tracing directroy. NULL can not be used as an error value. Instead, switch to ERR_PTR() and check the return status with IS_ERR(). Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 7669b1f3234e..acd27555dc5b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5820,7 +5820,7 @@ struct dentry *tracing_init_dentry_tr(struct trace_array *tr) return tr->dir; if (!debugfs_initialized()) - return NULL; + return ERR_PTR(-ENODEV); if (tr->flags & TRACE_ARRAY_FL_GLOBAL) tr->dir = debugfs_create_dir("tracing", NULL); @@ -5844,7 +5844,7 @@ static struct dentry *tracing_dentry_percpu(struct trace_array *tr, int cpu) return tr->percpu_dir; d_tracer = tracing_init_dentry_tr(tr); - if (!d_tracer) + if (IS_ERR(d_tracer)) return NULL; tr->percpu_dir = debugfs_create_dir("per_cpu", d_tracer); @@ -6047,7 +6047,7 @@ static struct dentry *trace_options_init_dentry(struct trace_array *tr) return tr->options; d_tracer = tracing_init_dentry_tr(tr); - if (!d_tracer) + if (IS_ERR(d_tracer)) return NULL; tr->options = debugfs_create_dir("options", d_tracer); @@ -6538,7 +6538,7 @@ static __init int tracer_init_debugfs(void) trace_access_lock_init(); d_tracer = tracing_init_dentry(); - if (!d_tracer) + if (IS_ERR(d_tracer)) return 0; init_tracer_debugfs(&global_trace, d_tracer); -- cgit v1.2.2 From 69a1c994cc540cc84469acf9952f72b899b38e8b Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Tue, 27 Jan 2015 17:17:20 +0100 Subject: tracing: Remove newline from trace_printk warning banner Remove the output-confusing newline below: [ 0.191328] ********************************************************** [ 0.191493] ** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE ** [ 0.191586] ** ** ... Link: http://lkml.kernel.org/r/1422375440-31970-1-git-send-email-bp@alien8.de Signed-off-by: Borislav Petkov [ added an extra '\n' by itself, to keep what it was suppose to do ] Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index acd27555dc5b..f82e53b0e5a7 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2036,7 +2036,8 @@ void trace_printk_init_buffers(void) /* trace_printk() is for debug use only. Don't use it in production. */ - pr_warning("\n**********************************************************\n"); + pr_warning("\n"); + pr_warning("**********************************************************\n"); pr_warning("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n"); pr_warning("** **\n"); pr_warning("** trace_printk() being used. Allocating extra memory. **\n"); -- cgit v1.2.2 From c602894814adc93589dde028182101818c5f938b Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Mon, 26 Jan 2015 20:38:39 -0500 Subject: tracing: Make tracing_init_dentry_tr() static tracing_init_dentry_tr() is not used outside of trace.c, it should be static. Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index f82e53b0e5a7..2668a0d742ee 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5815,7 +5815,7 @@ static __init int register_snapshot_cmd(void) static inline __init int register_snapshot_cmd(void) { return 0; } #endif /* defined(CONFIG_TRACER_SNAPSHOT) && defined(CONFIG_DYNAMIC_FTRACE) */ -struct dentry *tracing_init_dentry_tr(struct trace_array *tr) +static struct dentry *tracing_init_dentry_tr(struct trace_array *tr) { if (tr->dir) return tr->dir; -- cgit v1.2.2 From 7eeafbcab47fe9860e5106286db83d60e3f35644 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Mon, 26 Jan 2015 21:00:48 -0500 Subject: tracing: Separate out initializing top level dir from instances The top level trace array is treated a little different than the instances, as it has to deal with more of the general tracing. The tr->dir is the tracing directory, which is an immutable dentry, where as the tr->dir of instances are the dentry that was created, and can be destroyed later. These should have different functions accessing them. As only tracing_init_dentry() deals with the top level array, fold the code for it into that function, and remove the trace_init_dentry_tr() that was also used by the instances to get their directory dentry. Add a tracing_get_dentry() to just get the tracing dir entry for instances as well as the top level array. Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 51 ++++++++++++++++++++++++++++++--------------------- 1 file changed, 30 insertions(+), 21 deletions(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 2668a0d742ee..5afce60e1b68 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5815,28 +5815,11 @@ static __init int register_snapshot_cmd(void) static inline __init int register_snapshot_cmd(void) { return 0; } #endif /* defined(CONFIG_TRACER_SNAPSHOT) && defined(CONFIG_DYNAMIC_FTRACE) */ -static struct dentry *tracing_init_dentry_tr(struct trace_array *tr) +static struct dentry *tracing_get_dentry(struct trace_array *tr) { - if (tr->dir) - return tr->dir; - - if (!debugfs_initialized()) - return ERR_PTR(-ENODEV); - - if (tr->flags & TRACE_ARRAY_FL_GLOBAL) - tr->dir = debugfs_create_dir("tracing", NULL); - - if (!tr->dir) - pr_warn_once("Could not create debugfs directory 'tracing'\n"); - return tr->dir; } -struct dentry *tracing_init_dentry(void) -{ - return tracing_init_dentry_tr(&global_trace); -} - static struct dentry *tracing_dentry_percpu(struct trace_array *tr, int cpu) { struct dentry *d_tracer; @@ -5844,7 +5827,7 @@ static struct dentry *tracing_dentry_percpu(struct trace_array *tr, int cpu) if (tr->percpu_dir) return tr->percpu_dir; - d_tracer = tracing_init_dentry_tr(tr); + d_tracer = tracing_get_dentry(tr); if (IS_ERR(d_tracer)) return NULL; @@ -6047,7 +6030,7 @@ static struct dentry *trace_options_init_dentry(struct trace_array *tr) if (tr->options) return tr->options; - d_tracer = tracing_init_dentry_tr(tr); + d_tracer = tracing_get_dentry(tr); if (IS_ERR(d_tracer)) return NULL; @@ -6532,6 +6515,33 @@ init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer) } +/** + * tracing_init_dentry - initialize top level trace array + * + * This is called when creating files or directories in the tracing + * directory. It is called via fs_initcall() by any of the boot up code + * and expects to return the dentry of the top level tracing directory. + */ +struct dentry *tracing_init_dentry(void) +{ + struct trace_array *tr = &global_trace; + + if (tr->dir) + return tr->dir; + + if (WARN_ON(!debugfs_initialized())) + return ERR_PTR(-ENODEV); + + tr->dir = debugfs_create_dir("tracing", NULL); + + if (!tr->dir) { + pr_warn_once("Could not create debugfs directory 'tracing'\n"); + return ERR_PTR(-ENOMEM); + } + + return tr->dir; +} + static __init int tracer_init_debugfs(void) { struct dentry *d_tracer; @@ -6772,7 +6782,6 @@ __init static int tracer_alloc_buffers(void) int ring_buf_size; int ret = -ENOMEM; - if (!alloc_cpumask_var(&tracing_buffer_mask, GFP_KERNEL)) goto out; -- cgit v1.2.2 From 7215853e985a4bef1a6c14e00e89dfec84f1e457 Mon Sep 17 00:00:00 2001 From: Vikram Mulukutla Date: Wed, 17 Dec 2014 18:50:56 -0800 Subject: tracing: Fix unmapping loop in tracing_mark_write Commit 6edb2a8a385f0cdef51dae37ff23e74d76d8a6ce introduced an array map_pages that contains the addresses returned by kmap_atomic. However, when unmapping those pages, map_pages[0] is unmapped before map_pages[1], breaking the nesting requirement as specified in the documentation for kmap_atomic/kunmap_atomic. This was caught by the highmem debug code present in kunmap_atomic. Fix the loop to do the unmapping properly. Link: http://lkml.kernel.org/r/1418871056-6614-1-git-send-email-markivx@codeaurora.org Cc: stable@vger.kernel.org # 3.5+ Reviewed-by: Stephen Boyd Reported-by: Lime Yang Signed-off-by: Vikram Mulukutla Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 5afce60e1b68..2078b86750e0 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4928,7 +4928,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf, *fpos += written; out_unlock: - for (i = 0; i < nr_pages; i++){ + for (i = nr_pages - 1; i >= 0; i--) { kunmap_atomic(map_page[i]); put_page(pages[i]); } -- cgit v1.2.2