remove lots of IS_ERR_VALUE abuses

Most users of IS_ERR_VALUE() in the kernel are wrong, as they
pass an 'int' into a function that takes an 'unsigned long'
argument. This happens to work because the type is sign-extended
on 64-bit architectures before it gets converted into an
unsigned type.

However, anything that passes an 'unsigned short' or 'unsigned int'
argument into IS_ERR_VALUE() is guaranteed to be broken, as are
8-bit integers and types that are wider than 'unsigned long'.

Andrzej Hajda has already fixed a lot of the worst abusers that
were causing actual bugs, but it would be nice to prevent any
users that are not passing 'unsigned long' arguments.

This patch changes all users of IS_ERR_VALUE() that I could find
on 32-bit ARM randconfig builds and x86 allmodconfig. For the
moment, this doesn't change the definition of IS_ERR_VALUE()
because there are probably still architecture specific users
elsewhere.

Almost all the warnings I got are for files that are better off
using 'if (err)' or 'if (err < 0)'.
The only legitimate user I could find that we get a warning for
is the (32-bit only) freescale fman driver, so I did not remove
the IS_ERR_VALUE() there but changed the type to 'unsigned long'.
For 9pfs, I just worked around one user whose calling conventions
are so obscure that I did not dare change the behavior.

I was using this definition for testing:

 #define IS_ERR_VALUE(x) ((unsigned long*)NULL == (typeof (x)*)NULL && \
       unlikely((unsigned long long)(x) >= (unsigned long long)(typeof(x))-MAX_ERRNO))

which ends up making all 16-bit or wider types work correctly with
the most plausible interpretation of what IS_ERR_VALUE() was supposed
to return according to its users, but also causes a compile-time
warning for any users that do not pass an 'unsigned long' argument.

I suggested this approach earlier this year, but back then we ended
up deciding to just fix the users that are obviously broken. After
the initial warning that caused me to get involved in the discussion
(fs/gfs2/dir.c) showed up again in the mainline kernel, Linus
asked me to send the whole thing again.

[ Updated the 9p parts as per Al Viro  - Linus ]

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.org/lkml/2016/1/7/363
Link: https://lkml.org/lkml/2016/5/27/486
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> # For nvmem part
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 5 insertions, 5 deletions

diff --git a/drivers/net/ethernet/freescale/fman/fman.c b/drivers/net/ethernet/freescale/fman/fman.c
index bcb9dccada4d..1de2e1e51c2b 100644
--- a/drivers/net/ethernet/freescale/fman/fman.c
+++ b/drivers/net/ethernet/freescale/fman/fman.c
@@ -615,7 +615,7 @@ struct fman {
 	struct fman_cfg *cfg;
 	struct muram_info *muram;
 	/* cam section in muram */
-	int cam_offset;
+	unsigned long cam_offset;
 	size_t cam_size;
 	/* Fifo in MURAM */
 	int fifo_offset;
diff --git a/drivers/net/ethernet/freescale/fman/fman_muram.c b/drivers/net/ethernet/freescale/fman/fman_muram.c
index 4eb0e9ac7182..47394c45b6e8 100644
--- a/drivers/net/ethernet/freescale/fman/fman_muram.c
+++ b/drivers/net/ethernet/freescale/fman/fman_muram.c
@@ -129,7 +129,7 @@ unsigned long fman_muram_offset_to_vbase(struct muram_info *muram,
  *
  * Return: address of the allocated memory; NULL otherwise.
  */
-int fman_muram_alloc(struct muram_info *muram, size_t size)
+unsigned long fman_muram_alloc(struct muram_info *muram, size_t size)
 {
 	unsigned long vaddr;
 
@@ -150,7 +150,7 @@ int fman_muram_alloc(struct muram_info *muram, size_t size)
  *
  * Free an allocated memory from FM-MURAM partition.
  */
-void fman_muram_free_mem(struct muram_info *muram, u32 offset, size_t size)
+void fman_muram_free_mem(struct muram_info *muram, unsigned long offset, size_t size)
 {
 	unsigned long addr = fman_muram_offset_to_vbase(muram, offset);
 
diff --git a/drivers/net/ethernet/freescale/fman/fman_muram.h b/drivers/net/ethernet/freescale/fman/fman_muram.h
index dbf0af9e5bb5..889649ad8931 100644
--- a/drivers/net/ethernet/freescale/fman/fman_muram.h
+++ b/drivers/net/ethernet/freescale/fman/fman_muram.h
@@ -44,8 +44,8 @@ struct muram_info *fman_muram_init(phys_addr_t base, size_t size);
 unsigned long fman_muram_offset_to_vbase(struct muram_info *muram,
 					 unsigned long offset);
 
-int fman_muram_alloc(struct muram_info *muram, size_t size);
+unsigned long fman_muram_alloc(struct muram_info *muram, size_t size);
 
-void fman_muram_free_mem(struct muram_info *muram, u32 offset, size_t size);
+void fman_muram_free_mem(struct muram_info *muram, unsigned long offset, size_t size);
 
 #endif /* __FM_MURAM_EXT */