drivers/char/random.c:827:3: warning: format '%zd' expects argument of type 'signed size_t', but argument 7 has type 'size_t'

Quoted 27 lines · Andrew Morton

Quoted 23 lines · On Tue, 23 Oct 2012 18:16:58 +0800 Fengguang Wu <[email protected]> wrote:

Hi Jiri,

FYI, there are new compile warnings show up in

tree:   git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm
head:   dbfe0815b4af06cc4ca6cd12b17e2d13ffaaf991
commit: 0b1f5a647784c406ee33a6ddd3bb6382a2278111 [155/157] random: fix debug format strings
config: mn10300-asb2364_defconfig # make ARCH=mn10300 asb2364_defconfig

All warnings:

drivers/char/random.c: In function 'xfer_secondary_pool':
drivers/char/random.c:827:3: warning: format '%zd' expects argument of type 'signed size_t', but argument 7 has type 'size_t' [-Wformat] drivers/char/random.c: In function 'account':
drivers/char/random.c:859:2: warning: format '%zd' expects argument of type 'signed size_t', but argument 5 has type 'size_t' [-Wformat] drivers/char/random.c:881:2: warning: format '%zd' expects argument of type 'signed size_t', but argument 5 has type 'size_t' [-Wformat] drivers/char/random.c: In function 'random_read':
drivers/char/random.c:1141:3: warning: format '%zd' expects argument of type 'signed size_t', but argument 5 has type 'int' [-Wformat] drivers/char/random.c:1145:3: warning: format '%zd' expects argument of type 'signed size_t', but argument 5 has type 'int' [-Wformat] drivers/char/random.c:1145:3: warning: format '%zd' expects argument of type 'signed size_t', but argument 6 has type 'size_t' [-Wformat] drivers/char/random.c: In function 'write_pool':
drivers/char/random.c:1213:11: warning: comparison of distinct pointer types lacks a cast [enabled by default]

Quoted 1 line

Ah, I get it. %zd vs %zu. This?

With the patch, there are still errors (below). I think the reason of the warnings is, (size_t * 8) makes it an (int) because the constant 8 is (int).

CC drivers/char/random.o
/c/wfg/linux/drivers/char/random.c: In function 'xfer_secondary_pool':
/c/wfg/linux/drivers/char/random.c:827:3: warning: format '%zu' expects argument of type 'size_t', but argument 7 has type 'unsigned int' [-Wformat] /c/wfg/linux/drivers/char/random.c: In function 'account':
/c/wfg/linux/drivers/char/random.c:859:2: warning: format '%zu' expects argument of type 'size_t', but argument 5 has type 'unsigned int' [-Wformat] /c/wfg/linux/drivers/char/random.c:881:2: warning: format '%zu' expects argument of type 'size_t', but argument 5 has type 'unsigned int' [-Wformat] /c/wfg/linux/drivers/char/random.c: In function 'random_read':
/c/wfg/linux/drivers/char/random.c:1141:3: warning: format '%zu' expects argument of type 'size_t', but argument 5 has type 'int' [-Wformat] /c/wfg/linux/drivers/char/random.c:1145:3: warning: format '%zu' expects argument of type 'size_t', but argument 5 has type 'int' [-Wformat] /c/wfg/linux/drivers/char/random.c:1145:3: warning: format '%zu' expects argument of type 'size_t', but argument 6 has type 'unsigned int' [-Wformat]

And that behavior is depending on arch. Changing %zu to %u will make mn10300/parisc/i386 etc. archs compile cleanly, however x86_64 goes wrong like this:

/c/wfg/linux/drivers/char/random.c:827:3: warning: format ‘%u’ expects argument of type ‘unsigned int’, but argument 7 has type ‘size_t’ [-Wformat]

So in x86_64, (size_t * 8) is still of type size_t.

Thanks,
Fengguang
---

Quoted 68 lines

From: Andrew Morton <[email protected]>
Subject: random-fix-debug-format-strings-fix

s/%zd/%zu/ for unsigned `size_t'

Cc Jiri Kosina <[email protected]>

Cc Theodore Ts'o <[email protected]>

Signed-off-by Andrew Morton <[email protected]>

---

 drivers/char/random.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff -puN drivers/char/random.c~random-fix-debug-format-strings-fix drivers/char/random.c

drivers/char/random.c renamed from drivers/char/random.c~random-fix-debug-format-strings-fix +6 -6

@@ -825,7 +825,7 @@ static void xfer_secondary_pool(struct e
 		bytes = min_t(int, bytes, sizeof(tmp));
 
 		DEBUG_ENT("going to reseed %s with %d bits "
-			  "(%zd of %d requested)\n",
+			  "(%zu of %d requested)\n",
 			  r->name, bytes * 8, nbytes * 8, r->entropy_count);
 
 		bytes = extract_entropy(r->pull, tmp, bytes,

@@ -856,7 +856,7 @@ static size_t account(struct entropy_sto
 	spin_lock_irqsave(&r->lock, flags);
 
 	BUG_ON(r->entropy_count > r->poolinfo->POOLBITS);
-	DEBUG_ENT("trying to extract %zd bits from %s\n",
+	DEBUG_ENT("trying to extract %zu bits from %s\n",
 		  nbytes * 8, r->name);
 
 	/* Can we pull enough? */

@@ -878,7 +878,7 @@ static size_t account(struct entropy_sto
 		}
 	}
 
-	DEBUG_ENT("debiting %zd entropy credits from %s%s\n",
+	DEBUG_ENT("debiting %zu entropy credits from %s%s\n",
 		  nbytes * 8, r->name, r->limit ? "" : " (unlimited)");
 
 	spin_unlock_irqrestore(&r->lock, flags);

@@ -1138,11 +1138,11 @@ random_read(struct file *file, char __us
 		if (n > SEC_XFER_SIZE)
 			n = SEC_XFER_SIZE;
 
-		DEBUG_ENT("reading %zd bits\n", n*8);
+		DEBUG_ENT("reading %zu bits\n", n*8);
 
 		n = extract_entropy_user(&blocking_pool, buf, n);
 
-		DEBUG_ENT("read got %zd bits (%zd still needed)\n",
+		DEBUG_ENT("read got %zu bits (%zu still needed)\n",
 			  n*8, (nbytes-n)*8);
 
 		if (n == 0) {

@@ -1210,7 +1210,7 @@ write_pool(struct entropy_store *r, cons
 	const char __user *p = buffer;
 
 	while (count > 0) {
-		bytes = min(count, sizeof(buf));
+		bytes = min_t(size_t, count, sizeof(buf));
 		if (copy_from_user(&buf, p, bytes))
 			return -EFAULT;
 

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