Re: [PATCH] drm/radeon: silence GCC warning on 32 bit
On Thu, Feb 20, 2014 at 10:24:53PM +0100, Paul Bolle wrote:
> On Thu, 2014-02-20 at 16:07 -0500, Ilia Mirkin wrote:
> > On Thu, Feb 20, 2014 at 4:02 PM, Paul Bolle wrote:
> > > @@ -935,7 +935,7 @@ static ssize_t radeon_ttm_gtt_read(struct file *f,
> > > char __user *buf,
> > > while (size) {
> > > loff_t p = *pos / PAGE_SIZE;
> > > unsigned off = *pos & ~PAGE_MASK;
> > > - ssize_t cur_size = min(size, PAGE_SIZE - off);
> > > + ssize_t cur_size = min(size, (size_t)(PAGE_SIZE - off));
> >
> > Isn't the usual way of dealing with these to do something like
> >
> > ssize_t cur_size = min_t(ssize_t, size, PAGE_SIZE - off)
>
> I wouldn't know. I did
> $ git grep -n "(size_t)(PAGE_SIZE"
> arch/powerpc/mm/dma-noncoherent.c:357: size_t seg_size =
> min((size_t)(PAGE_SIZE - offset), size);
> arch/tile/kernel/pci-dma.c:176: size_t bytes = min(size,
> (size_t)(PAGE_SIZE - offset));
> arch/tile/kernel/pci-dma.c:192: size_t bytes = min(size,
> (size_t)(PAGE_SIZE - offset));
> drivers/net/wireless/ti/wlcore/main.c:806: len = min(maxlen,
> (size_t)(PAGE_SIZE - wl->fwlog_size));
> drivers/scsi/libfc/fc_libfc.c:143:
> (size_t)(PAGE_SIZE - (off & ~PAGE_MASK)));
> drivers/target/tcm_fc/tfc_io.c:160: tlen = min(tlen,
> (size_t)(PAGE_SIZE -
> drivers/target/tcm_fc/tfc_io.c:311: tlen = min(tlen,
> (size_t)(PAGE_SIZE -
>
> and concluded my solution was acceptable. Is your alternative considered
> to be better?
Yes, min_t() is specifically meant for this type of situation. On a side
note, I think cur_size should be size_t rather than ssize_t.
Thierry
pgpBR0tG5ijc2.pgp
Description: PGP signature
Re: [PATCH] drm/radeon: silence GCC warning on 32 bit
On Thu, 2014-02-20 at 16:07 -0500, Ilia Mirkin wrote:
> On Thu, Feb 20, 2014 at 4:02 PM, Paul Bolle wrote:
> > @@ -935,7 +935,7 @@ static ssize_t radeon_ttm_gtt_read(struct file *f, char
> > __user *buf,
> > while (size) {
> > loff_t p = *pos / PAGE_SIZE;
> > unsigned off = *pos & ~PAGE_MASK;
> > - ssize_t cur_size = min(size, PAGE_SIZE - off);
> > + ssize_t cur_size = min(size, (size_t)(PAGE_SIZE - off));
>
> Isn't the usual way of dealing with these to do something like
>
> ssize_t cur_size = min_t(ssize_t, size, PAGE_SIZE - off)
I wouldn't know. I did
$ git grep -n "(size_t)(PAGE_SIZE"
arch/powerpc/mm/dma-noncoherent.c:357: size_t seg_size =
min((size_t)(PAGE_SIZE - offset), size);
arch/tile/kernel/pci-dma.c:176: size_t bytes = min(size, (size_t)(PAGE_SIZE
- offset));
arch/tile/kernel/pci-dma.c:192: size_t bytes = min(size, (size_t)(PAGE_SIZE
- offset));
drivers/net/wireless/ti/wlcore/main.c:806: len = min(maxlen,
(size_t)(PAGE_SIZE - wl->fwlog_size));
drivers/scsi/libfc/fc_libfc.c:143:
(size_t)(PAGE_SIZE - (off & ~PAGE_MASK)));
drivers/target/tcm_fc/tfc_io.c:160: tlen = min(tlen,
(size_t)(PAGE_SIZE -
drivers/target/tcm_fc/tfc_io.c:311: tlen = min(tlen,
(size_t)(PAGE_SIZE -
and concluded my solution was acceptable. Is your alternative considered
to be better?
Paul Bolle
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Re: [PATCH] drm/radeon: silence GCC warning on 32 bit
On Thu, Feb 20, 2014 at 4:02 PM, Paul Bolle wrote:
> Building radeon_ttm.o on 32 bit x86 triggers a warning:
> In file included from include/asm-generic/bug.h:13:0,
> from [...]/arch/x86/include/asm/bug.h:38,
> from include/linux/bug.h:4,
> from include/drm/drm_mm.h:39,
> from include/drm/drm_vma_manager.h:26,
> from include/drm/ttm/ttm_bo_api.h:35,
> from drivers/gpu/drm/radeon/radeon_ttm.c:32:
> drivers/gpu/drm/radeon/radeon_ttm.c: In function 'radeon_ttm_gtt_read':
> include/linux/kernel.h:712:17: warning: comparison of distinct pointer
> types lacks a cast [enabled by default]
> (void) (&_min1 == &_min2); \
> ^
> drivers/gpu/drm/radeon/radeon_ttm.c:938:22: note: in expansion of macro
> 'min'
>ssize_t cur_size = min(size, PAGE_SIZE - off);
> ^
>
> Silence this warning by casting "PAGE_SIZE - off" to size_t. Since
> "PAGE_SIZE - off" is between 0 and PAGE_SIZE, and PAGE_SIZE is at most
> 21 bits wide while size_t is at least 32 bits wide, this should be safe.
>
> Signed-off-by: Paul Bolle
> ---
> Compile tested only (on 32 and 64 bit x86).
>
> drivers/gpu/drm/radeon/radeon_ttm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c
> b/drivers/gpu/drm/radeon/radeon_ttm.c
> index 77f5b0c..5c87979 100644
> --- a/drivers/gpu/drm/radeon/radeon_ttm.c
> +++ b/drivers/gpu/drm/radeon/radeon_ttm.c
> @@ -935,7 +935,7 @@ static ssize_t radeon_ttm_gtt_read(struct file *f, char
> __user *buf,
> while (size) {
> loff_t p = *pos / PAGE_SIZE;
> unsigned off = *pos & ~PAGE_MASK;
> - ssize_t cur_size = min(size, PAGE_SIZE - off);
> + ssize_t cur_size = min(size, (size_t)(PAGE_SIZE - off));
Isn't the usual way of dealing with these to do something like
ssize_t cur_size = min_t(ssize_t, size, PAGE_SIZE - off)
> struct page *page;
> void *ptr;
>
> --
> 1.8.5.3
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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[PATCH] drm/radeon: silence GCC warning on 32 bit
Building radeon_ttm.o on 32 bit x86 triggers a warning:
In file included from include/asm-generic/bug.h:13:0,
from [...]/arch/x86/include/asm/bug.h:38,
from include/linux/bug.h:4,
from include/drm/drm_mm.h:39,
from include/drm/drm_vma_manager.h:26,
from include/drm/ttm/ttm_bo_api.h:35,
from drivers/gpu/drm/radeon/radeon_ttm.c:32:
drivers/gpu/drm/radeon/radeon_ttm.c: In function 'radeon_ttm_gtt_read':
include/linux/kernel.h:712:17: warning: comparison of distinct pointer
types lacks a cast [enabled by default]
(void) (&_min1 == &_min2); \
^
drivers/gpu/drm/radeon/radeon_ttm.c:938:22: note: in expansion of macro
'min'
ssize_t cur_size = min(size, PAGE_SIZE - off);
^
Silence this warning by casting "PAGE_SIZE - off" to size_t. Since
"PAGE_SIZE - off" is between 0 and PAGE_SIZE, and PAGE_SIZE is at most
21 bits wide while size_t is at least 32 bits wide, this should be safe.
Signed-off-by: Paul Bolle
---
Compile tested only (on 32 and 64 bit x86).
drivers/gpu/drm/radeon/radeon_ttm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c
b/drivers/gpu/drm/radeon/radeon_ttm.c
index 77f5b0c..5c87979 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -935,7 +935,7 @@ static ssize_t radeon_ttm_gtt_read(struct file *f, char
__user *buf,
while (size) {
loff_t p = *pos / PAGE_SIZE;
unsigned off = *pos & ~PAGE_MASK;
- ssize_t cur_size = min(size, PAGE_SIZE - off);
+ ssize_t cur_size = min(size, (size_t)(PAGE_SIZE - off));
struct page *page;
void *ptr;
--
1.8.5.3
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