missing bits of "splice: fix racy pipe->buffers uses"

that commit has fixed only the parts of that mess in fs/splice.c itself;
there had been more in several other ->splice_read() instances...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7511de3..27924ca 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4410,7 +4410,7 @@
 	trace_access_lock(iter->cpu_file);
 
 	/* Fill as many pages as possible. */
-	for (i = 0, rem = len; i < pipe->buffers && rem; i++) {
+	for (i = 0, rem = len; i < spd.nr_pages_max && rem; i++) {
 		spd.pages[i] = alloc_page(GFP_KERNEL);
 		if (!spd.pages[i])
 			break;
@@ -5267,7 +5267,7 @@
 	trace_access_lock(iter->cpu_file);
 	entries = ring_buffer_entries_cpu(iter->trace_buffer->buffer, iter->cpu_file);
 
-	for (i = 0; i < pipe->buffers && len && entries; i++, len -= PAGE_SIZE) {
+	for (i = 0; i < spd.nr_pages_max && len && entries; i++, len -= PAGE_SIZE) {
 		struct page *page;
 		int r;