| Message ID | 20180709131600.GA9138@embeddedor.com |
|---|---|
| State | Rejected, archived |
| Headers | show |
| Series | ext4: use swap macro in mext_page_double_lock | expand |
On Mon, Jul 09, 2018 at 08:16:00AM -0500, Gustavo A. R. Silva wrote: > Make use of the swap macro and remove unnecessary variable *tmp*. > This makes the code easier to read and maintain. Also, reduces the > stack usage. > > This code was detected with the help of Coccinelle. > > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> It doesn't actually reduce stack usage. Look at the definition of swap() in include/linux/kernel.h: #define swap(a, b) \ do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0) It removes the variable "tmp", and replace it with "__tmp". It slightly reduces the number of lines of code, so it slightly makes the code easier to maintainer. But I think you are really over-promising how much this commit helps. Regards, - Ted
Hi Theodore, On 07/22/2018 05:19 PM, Theodore Y. Ts'o wrote: > On Mon, Jul 09, 2018 at 08:16:00AM -0500, Gustavo A. R. Silva wrote: >> Make use of the swap macro and remove unnecessary variable *tmp*. >> This makes the code easier to read and maintain. Also, reduces the >> stack usage. >> >> This code was detected with the help of Coccinelle. >> >> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> > > It doesn't actually reduce stack usage. Look at the definition of > swap() in include/linux/kernel.h: > > #define swap(a, b) \ > do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0) > > It removes the variable "tmp", and replace it with "__tmp". > > It slightly reduces the number of lines of code, so it slightly makes > the code easier to maintainer. But I think you are really > over-promising how much this commit helps. > I'll remove that part from the changelog and send it again. Thanks -- Gustavo
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c index 8e17efd..a409ff7 100644 --- a/fs/ext4/move_extent.c +++ b/fs/ext4/move_extent.c @@ -134,9 +134,7 @@ mext_page_double_lock(struct inode *inode1, struct inode *inode2, mapping[0] = inode1->i_mapping; mapping[1] = inode2->i_mapping; } else { - pgoff_t tmp = index1; - index1 = index2; - index2 = tmp; + swap(index1, index2); mapping[0] = inode2->i_mapping; mapping[1] = inode1->i_mapping; }
Make use of the swap macro and remove unnecessary variable *tmp*. This makes the code easier to read and maintain. Also, reduces the stack usage. This code was detected with the help of Coccinelle. Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> --- fs/ext4/move_extent.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)