Re: [PATCH] vhost: replace % with & on data path
From: "Michael S. Tsirkin" Date: Mon, 30 Nov 2015 10:34:07 +0200 > We know vring num is a power of 2, so use & > to mask the high bits. > > Signed-off-by: Michael S. Tsirkin > --- > drivers/vhost/vhost.c | 8 +--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index 080422f..85f0f0a 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -1366,10 +1366,12 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, > /* Only get avail ring entries after they have been exposed by guest. */ > smp_rmb(); > > + } > + !!! -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] vhost: replace % with & on data path
On Mon, Nov 30, 2015 at 12:42:49AM -0800, Joe Perches wrote: > On Mon, 2015-11-30 at 10:34 +0200, Michael S. Tsirkin wrote: > > We know vring num is a power of 2, so use & > > to mask the high bits. > [] > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > [] > > @@ -1366,10 +1366,12 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, > > /* Only get avail ring entries after they have been exposed by guest. */ > > smp_rmb(); > > > > + } > > ? Yes, I noticed this - I moved this chunk from the next patch in my tree by mistake. Will fix, thanks! -- MST -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] vhost: replace % with & on data path
Hi Michael,
[auto build test ERROR on: v4.4-rc3]
[also build test ERROR on: next-20151127]
url:
https://github.com/0day-ci/linux/commits/Michael-S-Tsirkin/vhost-replace-with-on-data-path/20151130-163704
config: x86_64-randconfig-s0-11301655 (attached as .config)
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64
All error/warnings (new ones prefixed by >>):
drivers/vhost/vhost.c: In function 'vhost_get_vq_desc':
drivers/vhost/vhost.c:1345:6: warning: unused variable 'ret'
[-Wunused-variable]
int ret;
^
drivers/vhost/vhost.c:1344:13: warning: unused variable 'ring_head'
[-Wunused-variable]
__virtio16 ring_head;
^
drivers/vhost/vhost.c:1341:24: warning: unused variable 'found'
[-Wunused-variable]
unsigned int i, head, found = 0;
^
drivers/vhost/vhost.c:1341:18: warning: unused variable 'head'
[-Wunused-variable]
unsigned int i, head, found = 0;
^
drivers/vhost/vhost.c:1341:15: warning: unused variable 'i'
[-Wunused-variable]
unsigned int i, head, found = 0;
^
drivers/vhost/vhost.c:1340:20: warning: unused variable 'desc'
[-Wunused-variable]
struct vring_desc desc;
^
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from include/uapi/linux/posix_types.h:4,
from include/uapi/linux/types.h:13,
from include/linux/types.h:5,
from include/uapi/asm-generic/fcntl.h:4,
from arch/x86/include/uapi/asm/fcntl.h:1,
from include/uapi/linux/fcntl.h:4,
from include/linux/fcntl.h:4,
from include/linux/eventfd.h:11,
from drivers/vhost/vhost.c:14:
drivers/vhost/vhost.c: At top level:
>> include/linux/compiler.h:147:2: error: expected identifier or '(' before 'if'
if (__builtin_constant_p((cond)) ? !!(cond) : \
^
include/linux/compiler.h:145:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^
>> drivers/vhost/vhost.c:1373:2: note: in expansion of macro 'if'
if (unlikely(__get_user(ring_head,
^
arch/x86/include/asm/uaccess.h:414:2: error: expected identifier or '('
before ')' token
})
^
include/linux/compiler.h:147:28: note: in definition of macro '__trace_if'
if (__builtin_constant_p((cond)) ? !!(cond) : \
^
>> drivers/vhost/vhost.c:1373:2: note: in expansion of macro 'if'
if (unlikely(__get_user(ring_head,
^
drivers/vhost/vhost.c:1373:6: note: in expansion of macro 'unlikely'
if (unlikely(__get_user(ring_head,
^
arch/x86/include/asm/uaccess.h:479:2: note: in expansion of macro
'__get_user_nocheck'
__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
^
drivers/vhost/vhost.c:1373:15: note: in expansion of macro '__get_user'
if (unlikely(__get_user(ring_head,
^
arch/x86/include/asm/uaccess.h:414:2: error: expected identifier or '('
before ')' token
})
^
include/linux/compiler.h:147:28: note: in definition of macro '__trace_if'
if (__builtin_constant_p((cond)) ? !!(cond) : \
^
>> drivers/vhost/vhost.c:1373:2: note: in expansion of macro 'if'
if (unlikely(__get_user(ring_head,
^
drivers/vhost/vhost.c:1373:6: note: in expansion of macro 'unlikely'
if (unlikely(__get_user(ring_head,
^
arch/x86/include/asm/uaccess.h:479:2: note: in expansion of macro
'__get_user_nocheck'
__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
^
drivers/vhost/vhost.c:1373:15: note: in expansion of macro '__get_user'
if (unlikely(__get_user(ring_head,
^
include/linux/compiler.h:126:4: error: expected identifier or '(' before ')'
token
})
^
include/linux/compiler.h:147:28: note: in definition of macro '__trace_if'
if (__builtin_constant_p((cond)) ? !!(cond) : \
^
>> drivers/vhost/vhost.c:1373:2: note: in expansion of macro 'if'
if (unlikely(__get_user(ring_head,
^
include/linux/compiler.h:137:58: note: in expansion of macro
'__branch_check__'
# define unlikely(x) (__builtin_constant_p(x) ? !!(x) :
__branch_check__(x, 0))
^
drivers/vhost/vhost.c:1373:6: note: in expansion of macro 'unlikely'
if (unlikely(__get_user(ring_head,
^
arch/x86/include/asm/uaccess.h:414:2: error: expected identifier or '('
before ')' token
})
^
include/linux/compiler.h:147:40: note: in definition of macro '__trace_if'
if (__builtin_constant_p((cond)) ? !!(cond) : \
^
>> drivers/
Re: [PATCH] vhost: replace % with & on data path
On Mon, Nov 30, 2015 at 10:34:07AM +0200, Michael S. Tsirkin wrote:
> We know vring num is a power of 2, so use &
> to mask the high bits.
>
> Signed-off-by: Michael S. Tsirkin
> ---
> drivers/vhost/vhost.c | 8 +---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 080422f..85f0f0a 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -1366,10 +1366,12 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
> /* Only get avail ring entries after they have been exposed by guest. */
> smp_rmb();
>
> + }
> +
Oops. This sneaked in from an unrelated patch.
Pls ignore, will repost.
> /* Grab the next descriptor number they're advertising, and increment
>* the index we've seen. */
> if (unlikely(__get_user(ring_head,
> - &vq->avail->ring[last_avail_idx % vq->num]))) {
> + &vq->avail->ring[last_avail_idx & (vq->num -
> 1)]))) {
> vq_err(vq, "Failed to read head: idx %d address %p\n",
> last_avail_idx,
> &vq->avail->ring[last_avail_idx % vq->num]);
> @@ -1489,7 +1491,7 @@ static int __vhost_add_used_n(struct vhost_virtqueue
> *vq,
> u16 old, new;
> int start;
>
> - start = vq->last_used_idx % vq->num;
> + start = vq->last_used_idx & (vq->num - 1);
> used = vq->used->ring + start;
> if (count == 1) {
> if (__put_user(heads[0].id, &used->id)) {
> @@ -1531,7 +1533,7 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, struct
> vring_used_elem *heads,
> {
> int start, n, r;
>
> - start = vq->last_used_idx % vq->num;
> + start = vq->last_used_idx & (vq->num - 1);
> n = vq->num - start;
> if (n < count) {
> r = __vhost_add_used_n(vq, heads, n);
> --
> MST
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] vhost: replace % with & on data path
Hi Michael,
[auto build test ERROR on: v4.4-rc3]
[also build test ERROR on: next-20151127]
url:
https://github.com/0day-ci/linux/commits/Michael-S-Tsirkin/vhost-replace-with-on-data-path/20151130-163704
config: i386-randconfig-s1-201548 (attached as .config)
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All error/warnings (new ones prefixed by >>):
drivers/vhost/vhost.c: In function 'vhost_get_vq_desc':
>> drivers/vhost/vhost.c:1345:6: warning: unused variable 'ret'
>> [-Wunused-variable]
int ret;
^
>> drivers/vhost/vhost.c:1344:13: warning: unused variable 'ring_head'
>> [-Wunused-variable]
__virtio16 ring_head;
^
>> drivers/vhost/vhost.c:1341:24: warning: unused variable 'found'
>> [-Wunused-variable]
unsigned int i, head, found = 0;
^
>> drivers/vhost/vhost.c:1341:18: warning: unused variable 'head'
>> [-Wunused-variable]
unsigned int i, head, found = 0;
^
>> drivers/vhost/vhost.c:1341:15: warning: unused variable 'i'
>> [-Wunused-variable]
unsigned int i, head, found = 0;
^
>> drivers/vhost/vhost.c:1340:20: warning: unused variable 'desc'
>> [-Wunused-variable]
struct vring_desc desc;
^
drivers/vhost/vhost.c: At top level:
>> drivers/vhost/vhost.c:1373:2: error: expected identifier or '(' before 'if'
if (unlikely(__get_user(ring_head,
^
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from include/uapi/linux/posix_types.h:4,
from include/uapi/linux/types.h:13,
from include/linux/types.h:5,
from include/uapi/asm-generic/fcntl.h:4,
from arch/x86/include/uapi/asm/fcntl.h:1,
from include/uapi/linux/fcntl.h:4,
from include/linux/fcntl.h:4,
from include/linux/eventfd.h:11,
from drivers/vhost/vhost.c:14:
>> arch/x86/include/asm/uaccess.h:414:2: error: expected identifier or '('
>> before ')' token
})
^
include/linux/compiler.h:137:45: note: in definition of macro 'unlikely'
# define unlikely(x) (__builtin_constant_p(x) ? !!(x) :
__branch_check__(x, 0))
^
arch/x86/include/asm/uaccess.h:479:2: note: in expansion of macro
'__get_user_nocheck'
__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
^
>> drivers/vhost/vhost.c:1373:15: note: in expansion of macro '__get_user'
if (unlikely(__get_user(ring_head,
^
>> arch/x86/include/asm/uaccess.h:414:2: error: expected identifier or '('
>> before ')' token
})
^
include/linux/compiler.h:137:53: note: in definition of macro 'unlikely'
# define unlikely(x) (__builtin_constant_p(x) ? !!(x) :
__branch_check__(x, 0))
^
arch/x86/include/asm/uaccess.h:479:2: note: in expansion of macro
'__get_user_nocheck'
__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
^
>> drivers/vhost/vhost.c:1373:15: note: in expansion of macro '__get_user'
if (unlikely(__get_user(ring_head,
^
>> include/linux/compiler.h:126:4: error: expected identifier or '(' before ')'
>> token
})
^
include/linux/compiler.h:137:58: note: in expansion of macro
'__branch_check__'
# define unlikely(x) (__builtin_constant_p(x) ? !!(x) :
__branch_check__(x, 0))
^
>> drivers/vhost/vhost.c:1373:6: note: in expansion of macro 'unlikely'
if (unlikely(__get_user(ring_head,
^
>> drivers/vhost/vhost.c:1381:2: warning: data definition has no type or
>> storage class
head = vhost16_to_cpu(vq, ring_head);
^
>> drivers/vhost/vhost.c:1381:2: error: type defaults to 'int' in declaration
>> of 'head' [-Werror=implicit-int]
>> drivers/vhost/vhost.c:1381:24: error: 'vq' undeclared here (not in a
>> function)
head = vhost16_to_cpu(vq, ring_head);
^
>> drivers/vhost/vhost.c:1381:28: error: 'ring_head' undeclared here (not in a
>> function)
head = vhost16_to_cpu(vq, ring_head);
^
drivers/vhost/vhost.c:1384:2: error: expected identifier or '(' before 'if'
if (unlikely(head >= vq->num)) {
^
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from include/uapi/linux/posix_types.h:4,
from include/uapi/linux/types.h:13,
from include/linux/types.h:5,
from include/uapi/asm-generic/fcntl.h:4,
from arch/x86/include/uapi/asm/fcntl.h:1,
from include/uapi/linux/fcntl.h:4,
from include/linux/fcntl.h:4,
Re: [PATCH] vhost: replace % with & on data path
Hi Michael,
[auto build test ERROR on: v4.4-rc3]
[also build test ERROR on: next-20151127]
url:
https://github.com/0day-ci/linux/commits/Michael-S-Tsirkin/vhost-replace-with-on-data-path/20151130-163704
config: s390-performance_defconfig (attached as .config)
reproduce:
wget
https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross
-O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
make.cross ARCH=s390
All errors (new ones prefixed by >>):
drivers/vhost/vhost.c: In function 'vhost_get_vq_desc':
drivers/vhost/vhost.c:1345:6: warning: unused variable 'ret'
[-Wunused-variable]
int ret;
^
drivers/vhost/vhost.c:1344:13: warning: unused variable 'ring_head'
[-Wunused-variable]
__virtio16 ring_head;
^
drivers/vhost/vhost.c:1341:24: warning: unused variable 'found'
[-Wunused-variable]
unsigned int i, head, found = 0;
^
drivers/vhost/vhost.c:1341:18: warning: unused variable 'head'
[-Wunused-variable]
unsigned int i, head, found = 0;
^
drivers/vhost/vhost.c:1341:15: warning: unused variable 'i'
[-Wunused-variable]
unsigned int i, head, found = 0;
^
drivers/vhost/vhost.c:1340:20: warning: unused variable 'desc'
[-Wunused-variable]
struct vring_desc desc;
^
drivers/vhost/vhost.c: At top level:
drivers/vhost/vhost.c:1373:2: error: expected identifier or '(' before 'if'
if (unlikely(__get_user(ring_head,
^
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from include/uapi/linux/posix_types.h:4,
from include/uapi/linux/types.h:13,
from include/linux/types.h:5,
from include/uapi/asm-generic/fcntl.h:4,
from arch/s390/include/uapi/asm/fcntl.h:1,
from include/uapi/linux/fcntl.h:4,
from include/linux/fcntl.h:4,
from include/linux/eventfd.h:11,
from drivers/vhost/vhost.c:14:
>> arch/s390/include/asm/uaccess.h:250:2: error: expected identifier or '('
>> before ')' token
})
^
include/linux/compiler.h:166:42: note: in definition of macro 'unlikely'
# define unlikely(x) __builtin_expect(!!(x), 0)
^
drivers/vhost/vhost.c:1373:15: note: in expansion of macro '__get_user'
if (unlikely(__get_user(ring_head,
^
drivers/vhost/vhost.c:1381:2: warning: data definition has no type or
storage class
head = vhost16_to_cpu(vq, ring_head);
^
drivers/vhost/vhost.c:1381:2: error: type defaults to 'int' in declaration
of 'head' [-Werror=implicit-int]
drivers/vhost/vhost.c:1381:24: error: 'vq' undeclared here (not in a
function)
head = vhost16_to_cpu(vq, ring_head);
^
drivers/vhost/vhost.c:1381:28: error: 'ring_head' undeclared here (not in a
function)
head = vhost16_to_cpu(vq, ring_head);
^
drivers/vhost/vhost.c:1384:2: error: expected identifier or '(' before 'if'
if (unlikely(head >= vq->num)) {
^
drivers/vhost/vhost.c:1391:2: warning: data definition has no type or
storage class
*out_num = *in_num = 0;
^
drivers/vhost/vhost.c:1391:3: error: type defaults to 'int' in declaration
of 'out_num' [-Werror=implicit-int]
*out_num = *in_num = 0;
^
drivers/vhost/vhost.c:1391:14: error: 'in_num' undeclared here (not in a
function)
*out_num = *in_num = 0;
^
drivers/vhost/vhost.c:1392:2: error: expected identifier or '(' before 'if'
if (unlikely(log))
^
drivers/vhost/vhost.c:1395:2: warning: data definition has no type or
storage class
i = head;
^
drivers/vhost/vhost.c:1395:2: error: type defaults to 'int' in declaration
of 'i' [-Werror=implicit-int]
drivers/vhost/vhost.c:1395:2: error: initializer element is not constant
drivers/vhost/vhost.c:1396:2: error: expected identifier or '(' before 'do'
do {
^
drivers/vhost/vhost.c:1454:4: error: expected identifier or '(' before
'while'
} while ((i = next_desc(vq, &desc)) != -1);
^
drivers/vhost/vhost.c:1457:4: error: expected '=', ',', ';', 'asm' or
'__attribute__' before '->' token
vq->last_avail_idx++;
^
In file included from arch/s390/include/asm/bug.h:69:0,
from include/linux/bug.h:4,
from include/linux/thread_info.h:11,
from include/asm-generic/preempt.h:4,
from arch/s390/include/generated/asm/preempt.h:1,
from include/linux/preempt.h:59,
from include/linux/spinlock.h:50,
from include/linux/wait.h:8,
Re: [PATCH] vhost: replace % with & on data path
On Mon, 2015-11-30 at 10:34 +0200, Michael S. Tsirkin wrote: > We know vring num is a power of 2, so use & > to mask the high bits. [] > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c [] > @@ -1366,10 +1366,12 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, > /* Only get avail ring entries after they have been exposed by guest. */ > smp_rmb(); > > + } ? -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
