diff mbox series

bitmap: Fix return values to be unsigned

Message ID 20220517035411.31144-1-keescook@chromium.org (mailing list archive)
State Superseded
Headers show
Series bitmap: Fix return values to be unsigned | expand

Commit Message

Kees Cook May 17, 2022, 3:54 a.m. UTC 
Both nodemask and bitmap routines had mixed return values that provided
potentially signed results that could never happen. This was leading to
the compiler getting confusing about the range of possible return values
(it was thinking things could be negative where they could not be). Fix
all the nodemask and bitmap routines that should be returning unsigned
(or bool) values. Silences GCC 12 warnings:

 mm/swapfile.c: In function ‘setup_swap_info’:
 mm/swapfile.c:2291:47: error: array subscript -1 is below array bounds of ‘struct plist_node[]’ [-Werror=array-bounds]
  2291 |                                 p->avail_lists[i].prio = 1;
       |                                 ~~~~~~~~~~~~~~^~~
 In file included from mm/swapfile.c:16:
 ./include/linux/swap.h:292:27: note: while referencing ‘avail_lists’
   292 |         struct plist_node avail_lists[]; /*
       |                           ^~~~~~~~~~~

Reported-by: Christophe de Dinechin <dinechin@redhat.com>
Link: https://lore.kernel.org/lkml/20220414150855.2407137-3-dinechin@redhat.com/
Cc: Yury Norov <yury.norov@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 include/linux/bitmap.h   | 14 +++++++-------
 include/linux/nodemask.h | 42 ++++++++++++++++++++--------------------
 lib/bitmap.c             | 28 +++++++++++++--------------
 lib/nodemask.c           |  6 +++---
 4 files changed, 45 insertions(+), 45 deletions(-)

Comments

Rasmus Villemoes May 17, 2022, 6:49 a.m. UTC | #1 
On 17/05/2022 05.54, Kees Cook wrote:
> Both nodemask and bitmap routines had mixed return values that provided
> potentially signed results that could never happen. This was leading to
> the compiler getting confusing about the range of possible return values
> (it was thinking things could be negative where they could not be). Fix
> all the nodemask and bitmap routines that should be returning unsigned
> (or bool) values. Silences GCC 12 warnings:

So, for the bitmap functions themselves, makes sense, and then also for
the nodemask functions which are merely wrappers around the bitmap
functions (or wrappers around wrappers ...). But see below.

>  
>  #define first_node(src) __first_node(&(src))
> -static inline int __first_node(const nodemask_t *srcp)
> +static inline unsigned int __first_node(const nodemask_t *srcp)
>  {
> -	return min_t(int, MAX_NUMNODES, find_first_bit(srcp->bits, MAX_NUMNODES));
> +	return min_t(unsigned int, MAX_NUMNODES, find_first_bit(srcp->bits, MAX_NUMNODES));
>  }

Unrelated to the type change, but what's that min() doing there in the
first place? Doesn't find_first_bit() already return the nbits argument
if no "first bit" exists (i.e., the bitmap is empty)?

>  #define next_node(n, src) __next_node((n), &(src))
> -static inline int __next_node(int n, const nodemask_t *srcp)
> +static inline unsigned int __next_node(int n, const nodemask_t *srcp)
>  {
> -	return min_t(int,MAX_NUMNODES,find_next_bit(srcp->bits, MAX_NUMNODES, n+1));
> +	return min_t(unsigned int, MAX_NUMNODES, find_next_bit(srcp->bits, MAX_NUMNODES, n+1));
>  }

Same here and a few more places.

It seems to go all the way back to pre-git. Hm. Could be cleaned up
separately I guess.

>  
>  #if defined(CONFIG_NUMA) && (MAX_NUMNODES > 1)
> -extern int node_random(const nodemask_t *maskp);
> +extern unsigned int node_random(const nodemask_t *maskp);

So this one I'm not convinced about. It has a documented return value of
NUMA_NO_NODE aka -1 if the mask is empty. And since it's not a wrapper
around a corresponding bitmap_random() (which would presumably, did it
exist, use the "return nbits if empty" convention), there's no
compelling reason to make its return type unsigned.

>  
> @@ -18,9 +18,9 @@ EXPORT_SYMBOL(__next_node_in);
>   * Return the bit number of a random bit set in the nodemask.
>   * (returns NUMA_NO_NODE if nodemask is empty)
>   */
> -int node_random(const nodemask_t *maskp)
> +unsigned int node_random(const nodemask_t *maskp)
>  {
> -	int w, bit = NUMA_NO_NODE;
> +	unsigned int w, bit = NUMA_NO_NODE;
>  
>  	w = nodes_weight(*maskp);
>  	if (w)

Rasmus
Kees Cook May 17, 2022, 9:15 p.m. UTC | #2 
On Tue, May 17, 2022 at 08:49:38AM +0200, Rasmus Villemoes wrote:
> On 17/05/2022 05.54, Kees Cook wrote:
> > Both nodemask and bitmap routines had mixed return values that provided
> > potentially signed results that could never happen. This was leading to
> > the compiler getting confusing about the range of possible return values
> > (it was thinking things could be negative where they could not be). Fix
> > all the nodemask and bitmap routines that should be returning unsigned
> > (or bool) values. Silences GCC 12 warnings:
> 
> So, for the bitmap functions themselves, makes sense, and then also for
> the nodemask functions which are merely wrappers around the bitmap
> functions (or wrappers around wrappers ...). But see below.

Cool. I think I should split this into two patches.

> 
> >  
> >  #define first_node(src) __first_node(&(src))
> > -static inline int __first_node(const nodemask_t *srcp)
> > +static inline unsigned int __first_node(const nodemask_t *srcp)
> >  {
> > -	return min_t(int, MAX_NUMNODES, find_first_bit(srcp->bits, MAX_NUMNODES));
> > +	return min_t(unsigned int, MAX_NUMNODES, find_first_bit(srcp->bits, MAX_NUMNODES));
> >  }
> 
> Unrelated to the type change, but what's that min() doing there in the
> first place? Doesn't find_first_bit() already return the nbits argument
> if no "first bit" exists (i.e., the bitmap is empty)?
> 
> >  #define next_node(n, src) __next_node((n), &(src))
> > -static inline int __next_node(int n, const nodemask_t *srcp)
> > +static inline unsigned int __next_node(int n, const nodemask_t *srcp)
> >  {
> > -	return min_t(int,MAX_NUMNODES,find_next_bit(srcp->bits, MAX_NUMNODES, n+1));
> > +	return min_t(unsigned int, MAX_NUMNODES, find_next_bit(srcp->bits, MAX_NUMNODES, n+1));
> >  }
> 
> Same here and a few more places.
> 
> It seems to go all the way back to pre-git. Hm. Could be cleaned up
> separately I guess.

Yeah, all I find as a hint is:

/* FIXME: better would be to fix all architectures to never return
          > MAX_NUMNODES, then the silly min_ts could be dropped. */

which also predates git history.

> 
> >  
> >  #if defined(CONFIG_NUMA) && (MAX_NUMNODES > 1)
> > -extern int node_random(const nodemask_t *maskp);
> > +extern unsigned int node_random(const nodemask_t *maskp);
> 
> So this one I'm not convinced about. It has a documented return value of
> NUMA_NO_NODE aka -1 if the mask is empty. And since it's not a wrapper
> around a corresponding bitmap_random() (which would presumably, did it
> exist, use the "return nbits if empty" convention), there's no
> compelling reason to make its return type unsigned.

Agreed; I'll drop this change.

Thanks!
diff mbox series

Patch

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 7dba0847510c..381735c2f2f1 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -132,8 +132,8 @@  unsigned long *devm_bitmap_zalloc(struct device *dev,
  * lib/bitmap.c provides these functions:
  */
 
-int __bitmap_equal(const unsigned long *bitmap1,
-		   const unsigned long *bitmap2, unsigned int nbits);
+bool __bitmap_equal(const unsigned long *bitmap1,
+		    const unsigned long *bitmap2, unsigned int nbits);
 bool __pure __bitmap_or_equal(const unsigned long *src1,
 			      const unsigned long *src2,
 			      const unsigned long *src3,
@@ -157,10 +157,10 @@  int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
 void __bitmap_replace(unsigned long *dst,
 		      const unsigned long *old, const unsigned long *new,
 		      const unsigned long *mask, unsigned int nbits);
-int __bitmap_intersects(const unsigned long *bitmap1,
-			const unsigned long *bitmap2, unsigned int nbits);
-int __bitmap_subset(const unsigned long *bitmap1,
-		    const unsigned long *bitmap2, unsigned int nbits);
+bool __bitmap_intersects(const unsigned long *bitmap1,
+			 const unsigned long *bitmap2, unsigned int nbits);
+bool __bitmap_subset(const unsigned long *bitmap1,
+		     const unsigned long *bitmap2, unsigned int nbits);
 int __bitmap_weight(const unsigned long *bitmap, unsigned int nbits);
 void __bitmap_set(unsigned long *map, unsigned int start, int len);
 void __bitmap_clear(unsigned long *map, unsigned int start, int len);
@@ -331,7 +331,7 @@  static inline void bitmap_complement(unsigned long *dst, const unsigned long *sr
 #endif
 #define BITMAP_MEM_MASK (BITMAP_MEM_ALIGNMENT - 1)
 
-static inline int bitmap_equal(const unsigned long *src1,
+static inline bool bitmap_equal(const unsigned long *src1,
 			const unsigned long *src2, unsigned int nbits)
 {
 	if (small_const_nbits(nbits))
diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index 567c3ddba2c4..6f89a39c1e9b 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -42,11 +42,11 @@ 
  * void nodes_shift_right(dst, src, n)	Shift right
  * void nodes_shift_left(dst, src, n)	Shift left
  *
- * int first_node(mask)			Number lowest set bit, or MAX_NUMNODES
- * int next_node(node, mask)		Next node past 'node', or MAX_NUMNODES
- * int next_node_in(node, mask)		Next node past 'node', or wrap to first,
+ * unsigned int first_node(mask)	Number lowest set bit, or MAX_NUMNODES
+ * unsigend int next_node(node, mask)	Next node past 'node', or MAX_NUMNODES
+ * unsigned int next_node_in(node, mask) Next node past 'node', or wrap to first,
  *					or MAX_NUMNODES
- * int first_unset_node(mask)		First node not set in mask, or 
+ * unsigned int first_unset_node(mask)	First node not set in mask, or
  *					MAX_NUMNODES
  *
  * nodemask_t nodemask_of_node(node)	Return nodemask with bit 'node' set
@@ -153,7 +153,7 @@  static inline void __nodes_clear(nodemask_t *dstp, unsigned int nbits)
 
 #define node_test_and_set(node, nodemask) \
 			__node_test_and_set((node), &(nodemask))
-static inline int __node_test_and_set(int node, nodemask_t *addr)
+static inline bool __node_test_and_set(int node, nodemask_t *addr)
 {
 	return test_and_set_bit(node, addr->bits);
 }
@@ -200,7 +200,7 @@  static inline void __nodes_complement(nodemask_t *dstp,
 
 #define nodes_equal(src1, src2) \
 			__nodes_equal(&(src1), &(src2), MAX_NUMNODES)
-static inline int __nodes_equal(const nodemask_t *src1p,
+static inline bool __nodes_equal(const nodemask_t *src1p,
 					const nodemask_t *src2p, unsigned int nbits)
 {
 	return bitmap_equal(src1p->bits, src2p->bits, nbits);
@@ -208,7 +208,7 @@  static inline int __nodes_equal(const nodemask_t *src1p,
 
 #define nodes_intersects(src1, src2) \
 			__nodes_intersects(&(src1), &(src2), MAX_NUMNODES)
-static inline int __nodes_intersects(const nodemask_t *src1p,
+static inline bool __nodes_intersects(const nodemask_t *src1p,
 					const nodemask_t *src2p, unsigned int nbits)
 {
 	return bitmap_intersects(src1p->bits, src2p->bits, nbits);
@@ -216,20 +216,20 @@  static inline int __nodes_intersects(const nodemask_t *src1p,
 
 #define nodes_subset(src1, src2) \
 			__nodes_subset(&(src1), &(src2), MAX_NUMNODES)
-static inline int __nodes_subset(const nodemask_t *src1p,
+static inline bool __nodes_subset(const nodemask_t *src1p,
 					const nodemask_t *src2p, unsigned int nbits)
 {
 	return bitmap_subset(src1p->bits, src2p->bits, nbits);
 }
 
 #define nodes_empty(src) __nodes_empty(&(src), MAX_NUMNODES)
-static inline int __nodes_empty(const nodemask_t *srcp, unsigned int nbits)
+static inline bool __nodes_empty(const nodemask_t *srcp, unsigned int nbits)
 {
 	return bitmap_empty(srcp->bits, nbits);
 }
 
 #define nodes_full(nodemask) __nodes_full(&(nodemask), MAX_NUMNODES)
-static inline int __nodes_full(const nodemask_t *srcp, unsigned int nbits)
+static inline bool __nodes_full(const nodemask_t *srcp, unsigned int nbits)
 {
 	return bitmap_full(srcp->bits, nbits);
 }
@@ -260,15 +260,15 @@  static inline void __nodes_shift_left(nodemask_t *dstp,
           > MAX_NUMNODES, then the silly min_ts could be dropped. */
 
 #define first_node(src) __first_node(&(src))
-static inline int __first_node(const nodemask_t *srcp)
+static inline unsigned int __first_node(const nodemask_t *srcp)
 {
-	return min_t(int, MAX_NUMNODES, find_first_bit(srcp->bits, MAX_NUMNODES));
+	return min_t(unsigned int, MAX_NUMNODES, find_first_bit(srcp->bits, MAX_NUMNODES));
 }
 
 #define next_node(n, src) __next_node((n), &(src))
-static inline int __next_node(int n, const nodemask_t *srcp)
+static inline unsigned int __next_node(int n, const nodemask_t *srcp)
 {
-	return min_t(int,MAX_NUMNODES,find_next_bit(srcp->bits, MAX_NUMNODES, n+1));
+	return min_t(unsigned int, MAX_NUMNODES, find_next_bit(srcp->bits, MAX_NUMNODES, n+1));
 }
 
 /*
@@ -276,7 +276,7 @@  static inline int __next_node(int n, const nodemask_t *srcp)
  * the first node in src if needed.  Returns MAX_NUMNODES if src is empty.
  */
 #define next_node_in(n, src) __next_node_in((n), &(src))
-int __next_node_in(int node, const nodemask_t *srcp);
+unsigned int __next_node_in(int node, const nodemask_t *srcp);
 
 static inline void init_nodemask_of_node(nodemask_t *mask, int node)
 {
@@ -296,9 +296,9 @@  static inline void init_nodemask_of_node(nodemask_t *mask, int node)
 })
 
 #define first_unset_node(mask) __first_unset_node(&(mask))
-static inline int __first_unset_node(const nodemask_t *maskp)
+static inline unsigned int __first_unset_node(const nodemask_t *maskp)
 {
-	return min_t(int,MAX_NUMNODES,
+	return min_t(unsigned int, MAX_NUMNODES,
 			find_first_zero_bit(maskp->bits, MAX_NUMNODES));
 }
 
@@ -436,11 +436,11 @@  static inline int num_node_state(enum node_states state)
 
 #define first_online_node	first_node(node_states[N_ONLINE])
 #define first_memory_node	first_node(node_states[N_MEMORY])
-static inline int next_online_node(int nid)
+static inline unsigned int next_online_node(int nid)
 {
 	return next_node(nid, node_states[N_ONLINE]);
 }
-static inline int next_memory_node(int nid)
+static inline unsigned int next_memory_node(int nid)
 {
 	return next_node(nid, node_states[N_MEMORY]);
 }
@@ -495,9 +495,9 @@  static inline int num_node_state(enum node_states state)
 #endif
 
 #if defined(CONFIG_NUMA) && (MAX_NUMNODES > 1)
-extern int node_random(const nodemask_t *maskp);
+extern unsigned int node_random(const nodemask_t *maskp);
 #else
-static inline int node_random(const nodemask_t *mask)
+static inline unsigned int node_random(const nodemask_t *mask)
 {
 	return 0;
 }
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 0d5c2ece0bcb..b57dafe13eec 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -45,19 +45,19 @@ 
  * for the best explanations of this ordering.
  */
 
-int __bitmap_equal(const unsigned long *bitmap1,
+bool __bitmap_equal(const unsigned long *bitmap1,
 		const unsigned long *bitmap2, unsigned int bits)
 {
 	unsigned int k, lim = bits/BITS_PER_LONG;
 	for (k = 0; k < lim; ++k)
 		if (bitmap1[k] != bitmap2[k])
-			return 0;
+			return false;
 
 	if (bits % BITS_PER_LONG)
 		if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
-			return 0;
+			return false;
 
-	return 1;
+	return true;
 }
 EXPORT_SYMBOL(__bitmap_equal);
 
@@ -303,33 +303,33 @@  void __bitmap_replace(unsigned long *dst,
 }
 EXPORT_SYMBOL(__bitmap_replace);
 
-int __bitmap_intersects(const unsigned long *bitmap1,
-			const unsigned long *bitmap2, unsigned int bits)
+bool __bitmap_intersects(const unsigned long *bitmap1,
+			 const unsigned long *bitmap2, unsigned int bits)
 {
 	unsigned int k, lim = bits/BITS_PER_LONG;
 	for (k = 0; k < lim; ++k)
 		if (bitmap1[k] & bitmap2[k])
-			return 1;
+			return true;
 
 	if (bits % BITS_PER_LONG)
 		if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
-			return 1;
-	return 0;
+			return true;
+	return false;
 }
 EXPORT_SYMBOL(__bitmap_intersects);
 
-int __bitmap_subset(const unsigned long *bitmap1,
-		    const unsigned long *bitmap2, unsigned int bits)
+bool __bitmap_subset(const unsigned long *bitmap1,
+		     const unsigned long *bitmap2, unsigned int bits)
 {
 	unsigned int k, lim = bits/BITS_PER_LONG;
 	for (k = 0; k < lim; ++k)
 		if (bitmap1[k] & ~bitmap2[k])
-			return 0;
+			return false;
 
 	if (bits % BITS_PER_LONG)
 		if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
-			return 0;
-	return 1;
+			return false;
+	return true;
 }
 EXPORT_SYMBOL(__bitmap_subset);
 
diff --git a/lib/nodemask.c b/lib/nodemask.c
index 3aa454c54c0d..6bac975fad7e 100644
--- a/lib/nodemask.c
+++ b/lib/nodemask.c
@@ -3,7 +3,7 @@ 
 #include <linux/module.h>
 #include <linux/random.h>
 
-int __next_node_in(int node, const nodemask_t *srcp)
+unsigned int __next_node_in(int node, const nodemask_t *srcp)
 {
 	int ret = __next_node(node, srcp);
 
@@ -18,9 +18,9 @@  EXPORT_SYMBOL(__next_node_in);
  * Return the bit number of a random bit set in the nodemask.
  * (returns NUMA_NO_NODE if nodemask is empty)
  */
-int node_random(const nodemask_t *maskp)
+unsigned int node_random(const nodemask_t *maskp)
 {
-	int w, bit = NUMA_NO_NODE;
+	unsigned int w, bit = NUMA_NO_NODE;
 
 	w = nodes_weight(*maskp);
 	if (w)