Subject: Re: [PATCH -next] samples/vfs/mountinfo: Use __u64 instead of uint64_t

From: Jeff Layton <[email-masked]>
Date: Mon, 06 Jan 2025 12:40:03 -0500

On Mon, 2025-01-06 at 14:48 +0100, Geert Uytterhoeven wrote:
> On 32-bit (e.g. arm32, m68k):
> 
>     samples/vfs/mountinfo.c: In function ‘dump_mountinfo’:
>     samples/vfs/mountinfo.c:145:29: warning: format ‘%lx’ expects argument of type ‘long unsigned int’, but argument 2 has type ‘uint64_t’ {aka ‘long long unsigned int’} [-Wformat=]
>       145 |                 printf("0x%lx 0x%lx 0x%llx ", mnt_ns_id, mnt_id, buf->mnt_parent_id);
> 	  |                           ~~^                 ~~~~~~~~~
> 	  |                             |                 |
> 	  |                             long unsigned int uint64_t {aka long long unsigned int}
> 	  |                           %llx
>     samples/vfs/mountinfo.c:145:35: warning: format ‘%lx’ expects argument of type ‘long unsigned int’, but argument 3 has type ‘uint64_t’ {aka ‘long long unsigned int’} [-Wformat=]
>       145 |                 printf("0x%lx 0x%lx 0x%llx ", mnt_ns_id, mnt_id, buf->mnt_parent_id);
> 	  |                                 ~~^                      ~~~~~~
> 	  |                                   |                      |
> 	  |                                   long unsigned int      uint64_t {aka long long unsigned int}
> 	  |                                 %llx
> 
> Just using "%llx" instead of "%lx" is not sufficient, as uint64_t is
> "long unsigned int" on some 64-bit platforms like arm64.  Hence also
> replace "uint64_t" by "__u64", which matches what most other samples
> are already using.
> 
> Fixes: d95e49bf8bcdc7c1 ("samples: add a mountinfo program to demonstrate statmount()/listmount()")
> Signed-off-by: Geert Uytterhoeven <[email-masked]>
> ---
> Feel free to fold into the original commit.
> 
> Alternatively, you can use PRIx64, which is used by tools/, but not by
> any of the current samples.
> ---
>  samples/vfs/mountinfo.c | 35 +++++++++++++++++------------------
>  1 file changed, 17 insertions(+), 18 deletions(-)
> 
> diff --git a/samples/vfs/mountinfo.c b/samples/vfs/mountinfo.c
> index 2b17d244d321ee75..f47c035cc339544e 100644
> --- a/samples/vfs/mountinfo.c
> +++ b/samples/vfs/mountinfo.c
> @@ -32,9 +32,9 @@ static bool ext_format;
>   * There are no bindings in glibc for listmount() and statmount() (yet),
>   * make our own here.
>   */
> -static int statmount(uint64_t mnt_id, uint64_t mnt_ns_id, uint64_t mask,
> -			    struct statmount *buf, size_t bufsize,
> -			    unsigned int flags)
> +static int statmount(__u64 mnt_id, __u64 mnt_ns_id, __u64 mask,
> +		     struct statmount *buf, size_t bufsize,
> +		     unsigned int flags)
>  {
>  	struct mnt_id_req req = {
>  		.size = MNT_ID_REQ_SIZE_VER0,
> @@ -50,9 +50,8 @@ static int statmount(uint64_t mnt_id, uint64_t mnt_ns_id, uint64_t mask,
>  	return syscall(__NR_statmount, &req, buf, bufsize, flags);
>  }
>  
> -static ssize_t listmount(uint64_t mnt_id, uint64_t mnt_ns_id,
> -			 uint64_t last_mnt_id, uint64_t list[], size_t num,
> -			 unsigned int flags)
> +static ssize_t listmount(__u64 mnt_id, __u64 mnt_ns_id, __u64 last_mnt_id,
> +			 __u64 list[], size_t num, unsigned int flags)
>  {
>  	struct mnt_id_req req = {
>  		.size = MNT_ID_REQ_SIZE_VER0,
> @@ -68,7 +67,7 @@ static ssize_t listmount(uint64_t mnt_id, uint64_t mnt_ns_id,
>  	return syscall(__NR_listmount, &req, list, num, flags);
>  }
>  
> -static void show_mnt_attrs(uint64_t flags)
> +static void show_mnt_attrs(__u64 flags)
>  {
>  	printf("%s", flags & MOUNT_ATTR_RDONLY ? "ro" : "rw");
>  
> @@ -112,7 +111,7 @@ static void show_propagation(struct statmount *sm)
>  		printf(" unbindable");
>  }
>  
> -static void show_sb_flags(uint64_t flags)
> +static void show_sb_flags(__u64 flags)
>  {
>  	printf("%s", flags & MS_RDONLY ? "ro" : "rw");
>  	if (flags & MS_SYNCHRONOUS)
> @@ -125,15 +124,15 @@ static void show_sb_flags(uint64_t flags)
>  		printf(",lazytime");
>  }
>  
> -static int dump_mountinfo(uint64_t mnt_id, uint64_t mnt_ns_id)
> +static int dump_mountinfo(__u64 mnt_id, __u64 mnt_ns_id)
>  {
>  	int ret;
>  	struct statmount *buf = alloca(STATMOUNT_BUFSIZE);
> -	const uint64_t mask = STATMOUNT_SB_BASIC | STATMOUNT_MNT_BASIC |
> -				STATMOUNT_PROPAGATE_FROM | STATMOUNT_FS_TYPE |
> -				STATMOUNT_MNT_ROOT | STATMOUNT_MNT_POINT |
> -				STATMOUNT_MNT_OPTS | STATMOUNT_FS_SUBTYPE |
> -				STATMOUNT_SB_SOURCE;
> +	const __u64 mask = STATMOUNT_SB_BASIC | STATMOUNT_MNT_BASIC |
> +			   STATMOUNT_PROPAGATE_FROM | STATMOUNT_FS_TYPE |
> +			   STATMOUNT_MNT_ROOT | STATMOUNT_MNT_POINT |
> +			   STATMOUNT_MNT_OPTS | STATMOUNT_FS_SUBTYPE |
> +			   STATMOUNT_SB_SOURCE;
>  
>  	ret = statmount(mnt_id, mnt_ns_id, mask, buf, STATMOUNT_BUFSIZE, 0);
>  	if (ret < 0) {
> @@ -142,7 +141,7 @@ static int dump_mountinfo(uint64_t mnt_id, uint64_t mnt_ns_id)
>  	}
>  
>  	if (ext_format)
> -		printf("0x%lx 0x%lx 0x%llx ", mnt_ns_id, mnt_id, buf->mnt_parent_id);
> +		printf("0x%llx 0x%llx 0x%llx ", mnt_ns_id, mnt_id, buf->mnt_parent_id);
>  
>  	printf("%u %u %u:%u %s %s ", buf->mnt_id_old, buf->mnt_parent_id_old,
>  				   buf->sb_dev_major, buf->sb_dev_minor,
> @@ -166,10 +165,10 @@ static int dump_mountinfo(uint64_t mnt_id, uint64_t mnt_ns_id)
>  	return 0;
>  }
>  
> -static int dump_mounts(uint64_t mnt_ns_id)
> +static int dump_mounts(__u64 mnt_ns_id)
>  {
> -	uint64_t mntid[MAXMOUNTS];
> -	uint64_t last_mnt_id = 0;
> +	__u64 mntid[MAXMOUNTS];
> +	__u64 last_mnt_id = 0;
>  	ssize_t count;
>  	int i;
>  

Many thanks. I missed that bit of the fix.

Reviewed-by: Jeff Layton <[email-masked]>