From 34cd4998d38f9bd04f34b78a7cb0c7f1bee00bd9 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 9 Feb 2009 12:06:29 -0500 Subject: [PATCH] tracing: clean up splice code Ingo Molnar suggested a series of clean ups for the splice code. This patch implements those suggestions. Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 96 +++++++++++++++++++++++++------------------- 1 file changed, 55 insertions(+), 41 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 11fde0ad9cb6..d89821283b47 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2537,15 +2537,49 @@ static void tracing_spd_release_pipe(struct splice_pipe_desc *spd, } static struct pipe_buf_operations tracing_pipe_buf_ops = { - .can_merge = 0, - .map = generic_pipe_buf_map, - .unmap = generic_pipe_buf_unmap, - .confirm = generic_pipe_buf_confirm, - .release = tracing_pipe_buf_release, - .steal = generic_pipe_buf_steal, - .get = generic_pipe_buf_get, + .can_merge = 0, + .map = generic_pipe_buf_map, + .unmap = generic_pipe_buf_unmap, + .confirm = generic_pipe_buf_confirm, + .release = tracing_pipe_buf_release, + .steal = generic_pipe_buf_steal, + .get = generic_pipe_buf_get, }; +static size_t +tracing_fill_pipe_page(struct page *pages, size_t rem, + struct trace_iterator *iter) +{ + size_t count; + int ret; + + /* Seq buffer is page-sized, exactly what we need. */ + for (;;) { + count = iter->seq.len; + ret = print_trace_line(iter); + count = iter->seq.len - count; + if (rem < count) { + rem = 0; + iter->seq.len -= count; + break; + } + if (ret == TRACE_TYPE_PARTIAL_LINE) { + iter->seq.len -= count; + break; + } + + trace_consume(iter); + rem -= count; + if (!find_next_entry_inc(iter)) { + rem = 0; + iter->ent = NULL; + break; + } + } + + return rem; +} + static ssize_t tracing_splice_read_pipe(struct file *filp, loff_t *ppos, struct pipe_inode_info *pipe, @@ -2556,15 +2590,15 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, struct partial_page partial[PIPE_BUFFERS]; struct trace_iterator *iter = filp->private_data; struct splice_pipe_desc spd = { - .pages = pages, - .partial = partial, - .nr_pages = 0, /* This gets updated below. */ - .flags = flags, - .ops = &tracing_pipe_buf_ops, - .spd_release = tracing_spd_release_pipe, + .pages = pages, + .partial = partial, + .nr_pages = 0, /* This gets updated below. */ + .flags = flags, + .ops = &tracing_pipe_buf_ops, + .spd_release = tracing_spd_release_pipe, }; ssize_t ret; - size_t count, rem; + size_t rem; unsigned int i; mutex_lock(&trace_types_lock); @@ -2573,45 +2607,25 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, ret = iter->trace->splice_read(iter, filp, ppos, pipe, len, flags); if (ret) - goto out; + goto out_err; } ret = tracing_wait_pipe(filp); if (ret <= 0) - goto out; + goto out_err; if (!iter->ent && !find_next_entry_inc(iter)) { ret = -EFAULT; - goto out; + goto out_err; } /* Fill as many pages as possible. */ for (i = 0, rem = len; i < PIPE_BUFFERS && rem; i++) { pages[i] = alloc_page(GFP_KERNEL); + if (!pages[i]) + break; - /* Seq buffer is page-sized, exactly what we need. */ - for (;;) { - count = iter->seq.len; - ret = print_trace_line(iter); - count = iter->seq.len - count; - if (rem < count) { - rem = 0; - iter->seq.len -= count; - break; - } - if (ret == TRACE_TYPE_PARTIAL_LINE) { - iter->seq.len -= count; - break; - } - - trace_consume(iter); - rem -= count; - if (!find_next_entry_inc(iter)) { - rem = 0; - iter->ent = NULL; - break; - } - } + rem = tracing_fill_pipe_page(pages[i], rem, iter); /* Copy the data into the page, so we can start over. */ ret = trace_seq_to_buffer(&iter->seq, @@ -2633,7 +2647,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, return splice_to_pipe(pipe, &spd); -out: +out_err: mutex_unlock(&trace_types_lock); return ret; -- 2.20.1