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| author | Steven Rostedt <srostedt@redhat.com> | 2012-05-11 23:28:49 -0400 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2012-05-16 16:18:57 -0400 |
| commit | 6edb2a8a385f0cdef51dae37ff23e74d76d8a6ce (patch) | |
| tree | 80a8bf8b301984907bd8773ca31748e82e136638 | |
| parent | 978da300c7a65494692b329a6a4cbf364afc37c5 (diff) | |
| download | linux-6edb2a8a385f0cdef51dae37ff23e74d76d8a6ce.tar.bz2 | |
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@goodmis.org>
| -rw-r--r-- | 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 48ef4960ec90..d1b3469b62e3 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; } |