Messages in this thread Patch in this message | | | From | Linus Torvalds <> | Date | Mon, 28 Mar 2011 16:06:57 -0700 | Subject | Re: [GIT PULL] block drivers for 2.6.39-rc |
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On Sat, Mar 26, 2011 at 11:56 AM, Jens Axboe <jaxboe@fusionio.com> wrote: > Hi Linus, > > This is the pull request for the block driver updates for 2.6.39. Two > things here: > > - Big drbd update, as per usual... > - cciss update.
Btw, that cciss thing causes a very annoying compiler warning:
drivers/block/cciss.c: In function ‘dev_show_unique_id’: drivers/block/cciss.c:617:7: warning: ‘sn[0]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[1]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[2]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[3]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[4]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[5]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[6]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[7]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[8]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[9]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[10]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[11]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[12]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[13]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[14]’ may be used uninitialized in this function drivers/block/cciss.c:617:7: warning: ‘sn[15]’ may be used uninitialized in this function
which is because the compiler doesn't really notice that those things are only used if the error return isn't being set.
So it's a compiler mis-feature, but the thing is, the warning could easily be avoided by just writing the code more prettily.
Just do the memcpy() unconditionally: we know that 'drv' is a valid pointer (we just loaded 'h' off it), and we're talking about a nice constant 16-byte copy.
IOW, a patch something like the attached.
Untested, but it looks really obvious. Hmm?
Linus drivers/block/cciss.c | 19 +++++++++---------- 1 files changed, 9 insertions(+), 10 deletions(-)
diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c index 9bf1398..ec69f0c 100644 --- a/drivers/block/cciss.c +++ b/drivers/block/cciss.c @@ -619,22 +619,21 @@ static ssize_t dev_show_unique_id(struct device *dev, int ret = 0; spin_lock_irqsave(&h->lock, flags); + memcpy(sn, drv->serial_no, sizeof(sn)); if (h->busy_configuring) ret = -EBUSY; - else - memcpy(sn, drv->serial_no, sizeof(sn)); spin_unlock_irqrestore(&h->lock, flags); if (ret) return ret; - else - return snprintf(buf, 16 * 2 + 2, - "%02X%02X%02X%02X%02X%02X%02X%02X" - "%02X%02X%02X%02X%02X%02X%02X%02X\n", - sn[0], sn[1], sn[2], sn[3], - sn[4], sn[5], sn[6], sn[7], - sn[8], sn[9], sn[10], sn[11], - sn[12], sn[13], sn[14], sn[15]); + + return snprintf(buf, 16 * 2 + 2, + "%02X%02X%02X%02X%02X%02X%02X%02X" + "%02X%02X%02X%02X%02X%02X%02X%02X\n", + sn[0], sn[1], sn[2], sn[3], + sn[4], sn[5], sn[6], sn[7], + sn[8], sn[9], sn[10], sn[11], + sn[12], sn[13], sn[14], sn[15]); } static DEVICE_ATTR(unique_id, S_IRUGO, dev_show_unique_id, NULL); | |