From: Steven Rostedt The trace_pipe_raw never implemented polling and this was casing issues for several utilities. This is now implemented. Blocked reads still are on the TODO list. Reported-by: Mauro Carvalho Chehab Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 78 +++++++++++++++++++++++++++++++++----------------- 1 file changed, 51 insertions(+), 27 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 00e5e6e..b958e9d 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3503,10 +3503,8 @@ static int tracing_release_pipe(struct inode *inode, struct file *file) } static unsigned int -tracing_poll_pipe(struct file *filp, poll_table *poll_table) +trace_poll(struct trace_iterator *iter, struct file *filp, poll_table *poll_table) { - struct trace_iterator *iter = filp->private_data; - if (trace_flags & TRACE_ITER_BLOCK) { /* * Always select as readable when in blocking mode @@ -3515,6 +3513,7 @@ tracing_poll_pipe(struct file *filp, poll_table *poll_table) } else { if (!trace_empty(iter)) return POLLIN | POLLRDNORM; + trace_wakeup_needed = true; poll_wait(filp, &trace_wait, poll_table); if (!trace_empty(iter)) return POLLIN | POLLRDNORM; @@ -3523,6 +3522,14 @@ tracing_poll_pipe(struct file *filp, poll_table *poll_table) } } +static unsigned int +tracing_poll_pipe(struct file *filp, poll_table *poll_table) +{ + struct trace_iterator *iter = filp->private_data; + + return trace_poll(iter, filp, poll_table); +} + /* * This is a make-shift waitqueue. * A tracer might use this callback on some rare cases: @@ -4312,9 +4319,8 @@ static const struct file_operations snapshot_fops = { #endif /* CONFIG_TRACER_SNAPSHOT */ struct ftrace_buffer_info { - struct trace_array *tr; + struct trace_iterator iter; void *spare; - int cpu; unsigned int read; }; @@ -4331,22 +4337,32 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp) if (!info) return -ENOMEM; - info->tr = tr; - info->cpu = tc->cpu; - info->spare = NULL; + info->iter.tr = tr; + info->iter.cpu_file = tc->cpu; + info->spare = NULL; /* Force reading ring buffer for first read */ - info->read = (unsigned int)-1; + info->read = (unsigned int)-1; filp->private_data = info; return nonseekable_open(inode, filp); } +static unsigned int +tracing_buffers_poll(struct file *filp, poll_table *poll_table) +{ + struct ftrace_buffer_info *info = filp->private_data; + struct trace_iterator *iter = &info->iter; + + return trace_poll(iter, filp, poll_table); +} + static ssize_t tracing_buffers_read(struct file *filp, char __user *ubuf, size_t count, loff_t *ppos) { struct ftrace_buffer_info *info = filp->private_data; + struct trace_iterator *iter = &info->iter; ssize_t ret; size_t size; @@ -4354,7 +4370,7 @@ tracing_buffers_read(struct file *filp, char __user *ubuf, return 0; if (!info->spare) - info->spare = ring_buffer_alloc_read_page(info->tr->buffer, info->cpu); + info->spare = ring_buffer_alloc_read_page(iter->tr->buffer, iter->cpu_file); if (!info->spare) return -ENOMEM; @@ -4362,12 +4378,12 @@ tracing_buffers_read(struct file *filp, char __user *ubuf, if (info->read < PAGE_SIZE) goto read; - trace_access_lock(info->cpu); - ret = ring_buffer_read_page(info->tr->buffer, + trace_access_lock(iter->cpu_file); + ret = ring_buffer_read_page(iter->tr->buffer, &info->spare, count, - info->cpu, 0); - trace_access_unlock(info->cpu); + iter->cpu_file, 0); + trace_access_unlock(iter->cpu_file); if (ret < 0) return 0; @@ -4392,9 +4408,10 @@ read: static int tracing_buffers_release(struct inode *inode, struct file *file) { struct ftrace_buffer_info *info = file->private_data; + struct trace_iterator *iter = &info->iter; if (info->spare) - ring_buffer_free_read_page(info->tr->buffer, info->spare); + ring_buffer_free_read_page(iter->tr->buffer, info->spare); kfree(info); return 0; @@ -4461,6 +4478,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, unsigned int flags) { struct ftrace_buffer_info *info = file->private_data; + struct trace_iterator *iter = &info->iter; struct partial_page partial_def[PIPE_DEF_BUFFERS]; struct page *pages_def[PIPE_DEF_BUFFERS]; struct splice_pipe_desc spd = { @@ -4491,8 +4509,9 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, len &= PAGE_MASK; } - trace_access_lock(info->cpu); - entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu); + again: + trace_access_lock(iter->cpu_file); + entries = ring_buffer_entries_cpu(iter->tr->buffer, iter->cpu_file); for (i = 0; i < pipe->buffers && len && entries; i++, len -= PAGE_SIZE) { struct page *page; @@ -4503,15 +4522,15 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, break; ref->ref = 1; - ref->buffer = info->tr->buffer; - ref->page = ring_buffer_alloc_read_page(ref->buffer, info->cpu); + ref->buffer = iter->tr->buffer; + ref->page = ring_buffer_alloc_read_page(ref->buffer, iter->cpu_file); if (!ref->page) { kfree(ref); break; } r = ring_buffer_read_page(ref->buffer, &ref->page, - len, info->cpu, 1); + len, iter->cpu_file, 1); if (r < 0) { ring_buffer_free_read_page(ref->buffer, ref->page); kfree(ref); @@ -4535,20 +4554,24 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, spd.nr_pages++; *ppos += PAGE_SIZE; - entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu); + entries = ring_buffer_entries_cpu(iter->tr->buffer, iter->cpu_file); } - trace_access_unlock(info->cpu); + trace_access_unlock(iter->cpu_file); spd.nr_pages = i; /* did we read anything? */ if (!spd.nr_pages) { - if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK)) + if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK)) { ret = -EAGAIN; - else - ret = 0; - /* TODO: block */ - goto out; + goto out; + } + default_wait_pipe(iter); + if (signal_pending(current)) { + ret = -EINTR; + goto out; + } + goto again; } ret = splice_to_pipe(pipe, &spd); @@ -4560,6 +4583,7 @@ out: static const struct file_operations tracing_buffers_fops = { .open = tracing_buffers_open, .read = tracing_buffers_read, + .poll = tracing_buffers_poll, .release = tracing_buffers_release, .splice_read = tracing_buffers_splice_read, .llseek = no_llseek, -- 1.7.10.4 -- 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/