Commit-ID: 6edb2a8a385f0cdef51dae37ff23e74d76d8a6ce
Gitweb: http://git.kernel.org/tip/6edb2a8a385f0cdef51dae37ff23e74d76d8a6ce
Author: Steven Rostedt <srostedt@xxxxxxxxxx>
AuthorDate: Fri, 11 May 2012 23:28:49 -0400
Committer: Steven Rostedt <rostedt@xxxxxxxxxxx>
CommitDate: Wed, 16 May 2012 16:18:57 -0400
tracing: Clean up tracing_mark_write()
On gcc 4.5 the function tracing_mark_write() would give a warning
of page2 being uninitialized. This is due to a bug in gcc because
the logic prevents page2 from being used uninitialized, and
gcc 4.6+ does not complain (correctly).
Instead of adding a "unitialized" around page2, which could show
a bug later on, I combined page1 and page2 into an array map_pages[].
This binds the two and the two are modified according to nr_pages
(what gcc 4.5 seems to ignore). This no longer gives a warning with
gcc 4.5 nor with gcc 4.6.
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
kernel/trace/trace.c | 24 +++++++++++-------------
1 files changed, 11 insertions(+), 13 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 48ef496..d1b3469 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3875,14 +3875,14 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
struct print_entry *entry;
unsigned long irq_flags;
struct page *pages[2];
+ void *map_page[2];
int nr_pages = 1;
ssize_t written;
- void *page1;
- void *page2;
int offset;
int size;
int len;
int ret;
+ int i;
if (tracing_disabled)
return -EINVAL;
@@ -3921,9 +3921,8 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
goto out;
}
- page1 = kmap_atomic(pages[0]);
- if (nr_pages == 2)
- page2 = kmap_atomic(pages[1]);
+ for (i = 0; i < nr_pages; i++)
+ map_page[i] = kmap_atomic(pages[i]);
local_save_flags(irq_flags);
size = sizeof(*entry) + cnt + 2; /* possible \n added */
@@ -3941,10 +3940,10 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
if (nr_pages == 2) {
len = PAGE_SIZE - offset;
- memcpy(&entry->buf, page1 + offset, len);
- memcpy(&entry->buf[len], page2, cnt - len);
+ memcpy(&entry->buf, map_page[0] + offset, len);
+ memcpy(&entry->buf[len], map_page[1], cnt - len);
} else
- memcpy(&entry->buf, page1 + offset, cnt);
+ memcpy(&entry->buf, map_page[0] + offset, cnt);
if (entry->buf[cnt - 1] != '\n') {
entry->buf[cnt] = '\n';
@@ -3959,11 +3958,10 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
*fpos += written;
out_unlock:
- if (nr_pages == 2)
- kunmap_atomic(page2);
- kunmap_atomic(page1);
- while (nr_pages > 0)
- put_page(pages[--nr_pages]);
+ for (i = 0; i < nr_pages; i++){
+ kunmap_atomic(map_page[i]);
+ put_page(pages[i]);
+ }
out:
return written;
}
--
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