On Wed, 10 Jun 2015 19:36:43 +0200 (CEST)
Julia Lawall [off-list ref] wrote:

On Wed, 10 Jun 2015, walter harms wrote:

quoted

Am 10.06.2015 17:20, schrieb Firo Yang:

quoted

Warning like this:

drivers/md/md.c: In function ‘update_array_info’:
drivers/md/md.c:6394:26: warning: logical not is only applied
to the left hand side of comparison [-Wlogical-not-parentheses]
      !mddev->persistent  != info->not_persistent||

I fix it by enclosing !mddev->persistent with parentheses

By the way, I also fixed a line over 80 characters warning outputed
by ./scripts/checkpatch.pl

Signed-off-by: Firo Yang <redacted>
---
 drivers/md/md.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index dd85be9..b420d82 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c

@@ -6391,9 +6391,10 @@ static int update_array_info(struct mddev *mddev, mdu_array_info_t *info)
 	    mddev->ctime         != info->ctime         ||
 	    mddev->level         != info->level         ||
 /*	    mddev->layout        != info->layout        || */
-	    !mddev->persistent	 != info->not_persistent||
+	    (!mddev->persistent) != info->not_persistent ||

this looks odd,
would it be possible the check for == instead (and drop the !) ?
and it someone care for readability: It would be helpful to
make some more ifs here.

The original issue looks like a false positive.  If all of the other cases
have no parentheses on the left and use !=, isn't it better to leave the
code as is?

Leaving the code as it is would leave at least one compiler generating warnings.
I don't like warnings.
So if the compiler can be "fixed" that would be good.  But it seems unlikely.

May we could do:

quoted

quoted

+	    mddev->persistent != !info->not_persistent ||

That would keep the two "not"s together, avoid the need for parentheses, and
probably avoid the compiler warning.
(I think I had it the way it is because it almost reads 
   " not ...peristent != ... not_persistent"
but that isn't a strong reason)

Firo: Can you confirm that this version doesn't upset the compiler?
If if doesn't I'd definitely prefer this one. (and definitely leave out the
comment change - just change the code)

Thanks,
NeilBrown

julia

quoted

re,
 wh

quoted

 	    mddev->chunk_sectors != info->chunk_size >> 9 ||
-	    /* ignore bottom 8 bits of state, and allow SB_BITMAP_PRESENT to change */
+	    /* ignore bottom 8 bits of state, and allow SB_BITMAP_PRESENT
+		to change */
 	    ((state^info->state) & 0xfffffe00)
 		)
 		return -EINVAL;

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