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 <srostedt@redhat.com>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 11fde0a..d898212 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2537,15 +2537,49 @@
}
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 @@
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 @@
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 @@
return splice_to_pipe(pipe, &spd);
-out:
+out_err:
mutex_unlock(&trace_types_lock);
return ret;