Michael S. Tsirkin
2014-Nov-27 12:29 UTC
[PATCH v5 01/45] virtio: use u32, not bitmap for struct virtio_device's features
From: Rusty Russell <rusty at rustcorp.com.au>
It seemed like a good idea, but it's actually a pain when we get more
than 32 feature bits. Just change it to a u32 for now.
Cc: Brian Swetland <swetland at google.com>
Cc: Christian Borntraeger <borntraeger at de.ibm.com>
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
Signed-off-by: Cornelia Huck <cornelia.huck at de.ibm.com>
Acked-by: Pawel Moll <pawel.moll at arm.com>
Acked-by: Ohad Ben-Cohen <ohad at wizery.com>
Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
---
include/linux/virtio.h | 3 +--
include/linux/virtio_config.h | 2 +-
tools/virtio/linux/virtio.h | 22 +---------------------
tools/virtio/linux/virtio_config.h | 2 +-
drivers/char/virtio_console.c | 2 +-
drivers/lguest/lguest_device.c | 8 ++++----
drivers/misc/mic/card/mic_virtio.c | 2 +-
drivers/remoteproc/remoteproc_virtio.c | 2 +-
drivers/s390/kvm/kvm_virtio.c | 2 +-
drivers/s390/kvm/virtio_ccw.c | 23 +++++++++--------------
drivers/virtio/virtio.c | 10 +++++-----
drivers/virtio/virtio_mmio.c | 8 ++------
drivers/virtio/virtio_pci.c | 3 +--
drivers/virtio/virtio_ring.c | 2 +-
tools/virtio/virtio_test.c | 5 ++---
tools/virtio/vringh_test.c | 16 ++++++++--------
16 files changed, 40 insertions(+), 72 deletions(-)
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 65261a7..7828a7f 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -101,8 +101,7 @@ struct virtio_device {
const struct virtio_config_ops *config;
const struct vringh_config_ops *vringh_config;
struct list_head vqs;
- /* Note that this is a Linux set_bit-style bitmap. */
- unsigned long features[1];
+ u32 features;
void *priv;
};
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 7f4ef66..aa84d0e 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -93,7 +93,7 @@ static inline bool virtio_has_feature(const struct
virtio_device *vdev,
if (fbit < VIRTIO_TRANSPORT_F_START)
virtio_check_driver_offered_feature(vdev, fbit);
- return test_bit(fbit, vdev->features);
+ return vdev->features & (1 << fbit);
}
static inline
diff --git a/tools/virtio/linux/virtio.h b/tools/virtio/linux/virtio.h
index 5a2d1f0..72bff70 100644
--- a/tools/virtio/linux/virtio.h
+++ b/tools/virtio/linux/virtio.h
@@ -6,31 +6,11 @@
/* TODO: empty stubs for now. Broken but enough for virtio_ring.c */
#define list_add_tail(a, b) do {} while (0)
#define list_del(a) do {} while (0)
-
-#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
-#define BITS_PER_BYTE 8
-#define BITS_PER_LONG (sizeof(long) * BITS_PER_BYTE)
-#define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
-
-/* TODO: Not atomic as it should be:
- * we don't use this for anything important. */
-static inline void clear_bit(int nr, volatile unsigned long *addr)
-{
- unsigned long mask = BIT_MASK(nr);
- unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
-
- *p &= ~mask;
-}
-
-static inline int test_bit(int nr, const volatile unsigned long *addr)
-{
- return 1UL & (addr[BIT_WORD(nr)] >> (nr &
(BITS_PER_LONG-1)));
-}
/* end of stubs */
struct virtio_device {
void *dev;
- unsigned long features[1];
+ u32 features;
};
struct virtqueue {
diff --git a/tools/virtio/linux/virtio_config.h
b/tools/virtio/linux/virtio_config.h
index 5049967..1f1636b 100644
--- a/tools/virtio/linux/virtio_config.h
+++ b/tools/virtio/linux/virtio_config.h
@@ -2,5 +2,5 @@
#define VIRTIO_TRANSPORT_F_END 32
#define virtio_has_feature(dev, feature) \
- test_bit((feature), (dev)->features)
+ ((dev)->features & (1 << feature))
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index cf7a561..0074f9b 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -355,7 +355,7 @@ static inline bool use_multiport(struct ports_device
*portdev)
*/
if (!portdev->vdev)
return 0;
- return portdev->vdev->features[0] & (1 <<
VIRTIO_CONSOLE_F_MULTIPORT);
+ return portdev->vdev->features & (1 <<
VIRTIO_CONSOLE_F_MULTIPORT);
}
static DEFINE_SPINLOCK(dma_bufs_lock);
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index d0a1d8a..c831c47 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -137,14 +137,14 @@ static void lg_finalize_features(struct virtio_device
*vdev)
vring_transport_features(vdev);
/*
- * The vdev->feature array is a Linux bitmask: this isn't the same as a
- * the simple array of bits used by lguest devices for features. So we
- * do this slow, manual conversion which is completely general.
+ * Since lguest is currently x86-only, we're little-endian. That
+ * means we could just memcpy. But it's not time critical, and in
+ * case someone copies this code, we do it the slow, obvious way.
*/
memset(out_features, 0, desc->feature_len);
bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
for (i = 0; i < bits; i++) {
- if (test_bit(i, vdev->features))
+ if (vdev->features & (1 << i))
out_features[i / 8] |= (1 << (i % 8));
}
diff --git a/drivers/misc/mic/card/mic_virtio.c
b/drivers/misc/mic/card/mic_virtio.c
index e647947..0acd564 100644
--- a/drivers/misc/mic/card/mic_virtio.c
+++ b/drivers/misc/mic/card/mic_virtio.c
@@ -101,7 +101,7 @@ static void mic_finalize_features(struct virtio_device
*vdev)
bits = min_t(unsigned, feature_len,
sizeof(vdev->features)) * 8;
for (i = 0; i < bits; i++) {
- if (test_bit(i, vdev->features))
+ if (vdev->features & BIT(bits))
iowrite8(ioread8(&out_features[i / 8]) | (1 << (i % 8)),
&out_features[i / 8]);
}
diff --git a/drivers/remoteproc/remoteproc_virtio.c
b/drivers/remoteproc/remoteproc_virtio.c
index a34b506..dafaf38 100644
--- a/drivers/remoteproc/remoteproc_virtio.c
+++ b/drivers/remoteproc/remoteproc_virtio.c
@@ -231,7 +231,7 @@ static void rproc_virtio_finalize_features(struct
virtio_device *vdev)
* Remember the finalized features of our vdev, and provide it
* to the remote processor once it is powered on.
*/
- rsc->gfeatures = vdev->features[0];
+ rsc->gfeatures = vdev->features;
}
static void rproc_virtio_get(struct virtio_device *vdev, unsigned offset,
diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index 6431290..ac79a09 100644
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -106,7 +106,7 @@ static void kvm_finalize_features(struct virtio_device
*vdev)
memset(out_features, 0, desc->feature_len);
bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
for (i = 0; i < bits; i++) {
- if (test_bit(i, vdev->features))
+ if (vdev->features & (1 << i))
out_features[i / 8] |= (1 << (i % 8));
}
}
diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
index bda52f1..1dbee95 100644
--- a/drivers/s390/kvm/virtio_ccw.c
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -701,7 +701,6 @@ static void virtio_ccw_finalize_features(struct
virtio_device *vdev)
{
struct virtio_ccw_device *vcdev = to_vc_device(vdev);
struct virtio_feature_desc *features;
- int i;
struct ccw1 *ccw;
ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL);
@@ -715,19 +714,15 @@ static void virtio_ccw_finalize_features(struct
virtio_device *vdev)
/* Give virtio_ring a chance to accept features. */
vring_transport_features(vdev);
- for (i = 0; i < sizeof(*vdev->features) / sizeof(features->features);
- i++) {
- int highbits = i % 2 ? 32 : 0;
- features->index = i;
- features->features = cpu_to_le32(vdev->features[i / 2]
- >> highbits);
- /* Write the feature bits to the host. */
- ccw->cmd_code = CCW_CMD_WRITE_FEAT;
- ccw->flags = 0;
- ccw->count = sizeof(*features);
- ccw->cda = (__u32)(unsigned long)features;
- ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_FEAT);
- }
+ features->index = 0;
+ features->features = cpu_to_le32(vdev->features);
+ /* Write the feature bits to the host. */
+ ccw->cmd_code = CCW_CMD_WRITE_FEAT;
+ ccw->flags = 0;
+ ccw->count = sizeof(*features);
+ ccw->cda = (__u32)(unsigned long)features;
+ ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_FEAT);
+
out_free:
kfree(features);
kfree(ccw);
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index df598dd..7814b1f 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -49,9 +49,9 @@ static ssize_t features_show(struct device *_d,
/* We actually represent this as a bitstring, as it could be
* arbitrary length in future. */
- for (i = 0; i < ARRAY_SIZE(dev->features)*BITS_PER_LONG; i++)
+ for (i = 0; i < sizeof(dev->features)*8; i++)
len += sprintf(buf+len, "%c",
- test_bit(i, dev->features) ? '1' : '0');
+ dev->features & (1ULL << i) ? '1' :
'0');
len += sprintf(buf+len, "\n");
return len;
}
@@ -168,18 +168,18 @@ static int virtio_dev_probe(struct device *_d)
device_features = dev->config->get_features(dev);
/* Features supported by both device and driver into dev->features. */
- memset(dev->features, 0, sizeof(dev->features));
+ dev->features = 0;
for (i = 0; i < drv->feature_table_size; i++) {
unsigned int f = drv->feature_table[i];
BUG_ON(f >= 32);
if (device_features & (1 << f))
- set_bit(f, dev->features);
+ dev->features |= (1 << f);
}
/* Transport features always preserved to pass to finalize_features. */
for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
if (device_features & (1 << i))
- set_bit(i, dev->features);
+ dev->features |= (1 << i);
dev->config->finalize_features(dev);
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index ef9a165..eb5b0e2 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -155,16 +155,12 @@ static u32 vm_get_features(struct virtio_device *vdev)
static void vm_finalize_features(struct virtio_device *vdev)
{
struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
- int i;
/* Give virtio_ring a chance to accept features. */
vring_transport_features(vdev);
- for (i = 0; i < ARRAY_SIZE(vdev->features); i++) {
- writel(i, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES_SEL);
- writel(vdev->features[i],
- vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES);
- }
+ writel(0, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES_SEL);
+ writel(vdev->features, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES);
}
static void vm_get(struct virtio_device *vdev, unsigned offset,
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index d34ebfa..ab95a4c 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -120,8 +120,7 @@ static void vp_finalize_features(struct virtio_device *vdev)
vring_transport_features(vdev);
/* We only support 32 feature bits. */
- BUILD_BUG_ON(ARRAY_SIZE(vdev->features) != 1);
- iowrite32(vdev->features[0], vp_dev->ioaddr+VIRTIO_PCI_GUEST_FEATURES);
+ iowrite32(vdev->features, vp_dev->ioaddr+VIRTIO_PCI_GUEST_FEATURES);
}
/* virtio config->get() implementation */
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 3b1f89b..15a8a05 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -781,7 +781,7 @@ void vring_transport_features(struct virtio_device *vdev)
break;
default:
/* We don't understand this bit. */
- clear_bit(i, vdev->features);
+ vdev->features &= ~(1 << i);
}
}
}
diff --git a/tools/virtio/virtio_test.c b/tools/virtio/virtio_test.c
index 00ea679..db3437c 100644
--- a/tools/virtio/virtio_test.c
+++ b/tools/virtio/virtio_test.c
@@ -60,7 +60,7 @@ void vhost_vq_setup(struct vdev_info *dev, struct vq_info
*info)
{
struct vhost_vring_state state = { .index = info->idx };
struct vhost_vring_file file = { .index = info->idx };
- unsigned long long features = dev->vdev.features[0];
+ unsigned long long features = dev->vdev.features;
struct vhost_vring_addr addr = {
.index = info->idx,
.desc_user_addr = (uint64_t)(unsigned long)info->vring.desc,
@@ -113,8 +113,7 @@ static void vdev_info_init(struct vdev_info* dev, unsigned
long long features)
{
int r;
memset(dev, 0, sizeof *dev);
- dev->vdev.features[0] = features;
- dev->vdev.features[1] = features >> 32;
+ dev->vdev.features = features;
dev->buf_size = 1024;
dev->buf = malloc(dev->buf_size);
assert(dev->buf);
diff --git a/tools/virtio/vringh_test.c b/tools/virtio/vringh_test.c
index 14a4f4c..b6c9ee3 100644
--- a/tools/virtio/vringh_test.c
+++ b/tools/virtio/vringh_test.c
@@ -304,7 +304,7 @@ static int parallel_test(unsigned long features,
close(to_guest[1]);
close(to_host[0]);
- gvdev.vdev.features[0] = features;
+ gvdev.vdev.features = features;
gvdev.to_host_fd = to_host[1];
gvdev.notifies = 0;
@@ -449,13 +449,13 @@ int main(int argc, char *argv[])
bool fast_vringh = false, parallel = false;
getrange = getrange_iov;
- vdev.features[0] = 0;
+ vdev.features = 0;
while (argv[1]) {
if (strcmp(argv[1], "--indirect") == 0)
- vdev.features[0] |= (1 << VIRTIO_RING_F_INDIRECT_DESC);
+ vdev.features |= (1 << VIRTIO_RING_F_INDIRECT_DESC);
else if (strcmp(argv[1], "--eventidx") == 0)
- vdev.features[0] |= (1 << VIRTIO_RING_F_EVENT_IDX);
+ vdev.features |= (1 << VIRTIO_RING_F_EVENT_IDX);
else if (strcmp(argv[1], "--slow-range") == 0)
getrange = getrange_slow;
else if (strcmp(argv[1], "--fast-vringh") == 0)
@@ -468,7 +468,7 @@ int main(int argc, char *argv[])
}
if (parallel)
- return parallel_test(vdev.features[0], getrange, fast_vringh);
+ return parallel_test(vdev.features, getrange, fast_vringh);
if (posix_memalign(&__user_addr_min, PAGE_SIZE, USER_MEM) != 0)
abort();
@@ -483,7 +483,7 @@ int main(int argc, char *argv[])
/* Set up host side. */
vring_init(&vrh.vring, RINGSIZE, __user_addr_min, ALIGN);
- vringh_init_user(&vrh, vdev.features[0], RINGSIZE, true,
+ vringh_init_user(&vrh, vdev.features, RINGSIZE, true,
vrh.vring.desc, vrh.vring.avail, vrh.vring.used);
/* No descriptor to get yet... */
@@ -652,13 +652,13 @@ int main(int argc, char *argv[])
}
/* Test weird (but legal!) indirect. */
- if (vdev.features[0] & (1 << VIRTIO_RING_F_INDIRECT_DESC)) {
+ if (vdev.features & (1 << VIRTIO_RING_F_INDIRECT_DESC)) {
char *data = __user_addr_max - USER_MEM/4;
struct vring_desc *d = __user_addr_max - USER_MEM/2;
struct vring vring;
/* Force creation of direct, which we modify. */
- vdev.features[0] &= ~(1 << VIRTIO_RING_F_INDIRECT_DESC);
+ vdev.features &= ~(1 << VIRTIO_RING_F_INDIRECT_DESC);
vq = vring_new_virtqueue(0, RINGSIZE, ALIGN, &vdev, true,
__user_addr_min,
never_notify_host,
--
MST
David Hildenbrand
2014-Nov-27 16:15 UTC
[PATCH v5 01/45] virtio: use u32, not bitmap for struct virtio_device's features
> From: Rusty Russell <rusty at rustcorp.com.au> > > It seemed like a good idea, but it's actually a pain when we get more > than 32 feature bits. Just change it to a u32 for now. > > Cc: Brian Swetland <swetland at google.com> > Cc: Christian Borntraeger <borntraeger at de.ibm.com> > Signed-off-by: Rusty Russell <rusty at rustcorp.com.au> > Signed-off-by: Cornelia Huck <cornelia.huck at de.ibm.com> > Acked-by: Pawel Moll <pawel.moll at arm.com> > Acked-by: Ohad Ben-Cohen <ohad at wizery.com> > > Signed-off-by: Michael S. Tsirkin <mst at redhat.com> > ---Wouldn't it be easier to turn test_bit(i, dev->features) into a simple makro like #define test_bit(i, features) (features & (1 << i)) Similar one for clear_bit and set_bit. if names collide with existing functions, we could simply rename them to: set_feature_bit() ... clear_feature_bit() ...> diff --git a/drivers/misc/mic/card/mic_virtio.c b/drivers/misc/mic/card/mic_virtio.c > index e647947..0acd564 100644 > --- a/drivers/misc/mic/card/mic_virtio.c > +++ b/drivers/misc/mic/card/mic_virtio.c > @@ -101,7 +101,7 @@ static void mic_finalize_features(struct virtio_device *vdev) > bits = min_t(unsigned, feature_len, > sizeof(vdev->features)) * 8; > for (i = 0; i < bits; i++) { > - if (test_bit(i, vdev->features)) > + if (vdev->features & BIT(bits))Hm, shouldn't that also be "if (vdev->features & (1 << i))"?> iowrite8(ioread8(&out_features[i / 8]) | (1 << (i % 8)), > &out_features[i / 8]); > }> out_free: > kfree(features); > kfree(ccw); > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c > index df598dd..7814b1f 100644 > --- a/drivers/virtio/virtio.c > +++ b/drivers/virtio/virtio.c > @@ -49,9 +49,9 @@ static ssize_t features_show(struct device *_d, > > /* We actually represent this as a bitstring, as it could be > * arbitrary length in future. */ > - for (i = 0; i < ARRAY_SIZE(dev->features)*BITS_PER_LONG; i++) > + for (i = 0; i < sizeof(dev->features)*8; i++)... sizeof(dev->features) * 8; ... Do we have a define for 8 ?> len += sprintf(buf+len, "%c", > - test_bit(i, dev->features) ? '1' : '0'); > + dev->features & (1ULL << i) ? '1' : '0'); > len += sprintf(buf+len, "\n"); > return len; > } > @@ -168,18 +168,18 @@ static int virtio_dev_probe(struct device *_d) > device_features = dev->config->get_features(dev); >[...]> @@ -483,7 +483,7 @@ int main(int argc, char *argv[]) > > /* Set up host side. */ > vring_init(&vrh.vring, RINGSIZE, __user_addr_min, ALIGN); > - vringh_init_user(&vrh, vdev.features[0], RINGSIZE, true, > + vringh_init_user(&vrh, vdev.features, RINGSIZE, true, > vrh.vring.desc, vrh.vring.avail, vrh.vring.used); > > /* No descriptor to get yet... */ > @@ -652,13 +652,13 @@ int main(int argc, char *argv[]) > } > > /* Test weird (but legal!) indirect. */ > - if (vdev.features[0] & (1 << VIRTIO_RING_F_INDIRECT_DESC)) { > + if (vdev.features & (1 << VIRTIO_RING_F_INDIRECT_DESC)) { > char *data = __user_addr_max - USER_MEM/4; > struct vring_desc *d = __user_addr_max - USER_MEM/2; > struct vring vring; > > /* Force creation of direct, which we modify. */ > - vdev.features[0] &= ~(1 << VIRTIO_RING_F_INDIRECT_DESC); > + vdev.features &= ~(1 << VIRTIO_RING_F_INDIRECT_DESC);That could then be something like clear_feature_bit(VIRTIO_RING_F_INDIRECT_DESC, vdev.features); (I would prefer such makros over repeating bit actions)> vq = vring_new_virtqueue(0, RINGSIZE, ALIGN, &vdev, true, > __user_addr_min, > never_notify_host,But on the whole this looks good to me.
Michael S. Tsirkin
2014-Nov-27 16:28 UTC
[PATCH v5 01/45] virtio: use u32, not bitmap for struct virtio_device's features
On Thu, Nov 27, 2014 at 05:15:42PM +0100, David Hildenbrand wrote:> > From: Rusty Russell <rusty at rustcorp.com.au> > > > > It seemed like a good idea, but it's actually a pain when we get more > > than 32 feature bits. Just change it to a u32 for now. > > > > Cc: Brian Swetland <swetland at google.com> > > Cc: Christian Borntraeger <borntraeger at de.ibm.com> > > Signed-off-by: Rusty Russell <rusty at rustcorp.com.au> > > Signed-off-by: Cornelia Huck <cornelia.huck at de.ibm.com> > > Acked-by: Pawel Moll <pawel.moll at arm.com> > > Acked-by: Ohad Ben-Cohen <ohad at wizery.com> > > > > Signed-off-by: Michael S. Tsirkin <mst at redhat.com> > > --- > > Wouldn't it be easier to turn > test_bit(i, dev->features) > > into a simple makro like > #define test_bit(i, features) (features & (1 << i)) > > Similar one for clear_bit and set_bit.I don't really see why it's easier. These wrappers resulted in a ton of code converting from bit numbers to set_bit calls and back. E.g. with plan integer you can do (a|b|c) to get a set with 3 bits.> > if names collide with existing functions, we could simply rename them to: > > set_feature_bit() ... > clear_feature_bit() ...In fact that's why we have BIT macro. vdev->features & BIT_ULL(x) is only longer by 1 character than test_feature_bit(vdev, x), and it's much clearer than a non standard wrapper. vdev->features & (1ULL << x) is longer by 3 chars. I guess this is a suggestion to use BIT / BIT_ULL more. Good point.> > diff --git a/drivers/misc/mic/card/mic_virtio.c b/drivers/misc/mic/card/mic_virtio.c > > index e647947..0acd564 100644 > > --- a/drivers/misc/mic/card/mic_virtio.c > > +++ b/drivers/misc/mic/card/mic_virtio.c > > @@ -101,7 +101,7 @@ static void mic_finalize_features(struct virtio_device *vdev) > > bits = min_t(unsigned, feature_len, > > sizeof(vdev->features)) * 8; > > for (i = 0; i < bits; i++) { > > - if (test_bit(i, vdev->features)) > > + if (vdev->features & BIT(bits)) > > Hm, shouldn't that also be "if (vdev->features & (1 << i))"?Ouch. you are right of course. Will fix.> > iowrite8(ioread8(&out_features[i / 8]) | (1 << (i % 8)), > > &out_features[i / 8]); > > } > > > out_free: > > kfree(features); > > kfree(ccw); > > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c > > index df598dd..7814b1f 100644 > > --- a/drivers/virtio/virtio.c > > +++ b/drivers/virtio/virtio.c > > @@ -49,9 +49,9 @@ static ssize_t features_show(struct device *_d, > > > > /* We actually represent this as a bitstring, as it could be > > * arbitrary length in future. */ > > - for (i = 0; i < ARRAY_SIZE(dev->features)*BITS_PER_LONG; i++) > > + for (i = 0; i < sizeof(dev->features)*8; i++) > > ... sizeof(dev->features) * 8; ... > > Do we have a define for 8 ?We do: BITS_PER_BYTE.> > len += sprintf(buf+len, "%c", > > - test_bit(i, dev->features) ? '1' : '0'); > > + dev->features & (1ULL << i) ? '1' : '0'); > > len += sprintf(buf+len, "\n"); > > return len; > > } > > @@ -168,18 +168,18 @@ static int virtio_dev_probe(struct device *_d) > > device_features = dev->config->get_features(dev); > > > > [...] > > > @@ -483,7 +483,7 @@ int main(int argc, char *argv[]) > > > > /* Set up host side. */ > > vring_init(&vrh.vring, RINGSIZE, __user_addr_min, ALIGN); > > - vringh_init_user(&vrh, vdev.features[0], RINGSIZE, true, > > + vringh_init_user(&vrh, vdev.features, RINGSIZE, true, > > vrh.vring.desc, vrh.vring.avail, vrh.vring.used); > > > > /* No descriptor to get yet... */ > > @@ -652,13 +652,13 @@ int main(int argc, char *argv[]) > > } > > > > /* Test weird (but legal!) indirect. */ > > - if (vdev.features[0] & (1 << VIRTIO_RING_F_INDIRECT_DESC)) { > > + if (vdev.features & (1 << VIRTIO_RING_F_INDIRECT_DESC)) { > > char *data = __user_addr_max - USER_MEM/4; > > struct vring_desc *d = __user_addr_max - USER_MEM/2; > > struct vring vring; > > > > /* Force creation of direct, which we modify. */ > > - vdev.features[0] &= ~(1 << VIRTIO_RING_F_INDIRECT_DESC); > > + vdev.features &= ~(1 << VIRTIO_RING_F_INDIRECT_DESC); > > That could then be something like > > clear_feature_bit(VIRTIO_RING_F_INDIRECT_DESC, vdev.features); > > (I would prefer such makros over repeating bit actions)That's the whole reason for the patch. I guess you disagree with it, but it's much easier to deal with simple integers.> > vq = vring_new_virtqueue(0, RINGSIZE, ALIGN, &vdev, true, > > __user_addr_min, > > never_notify_host, > > > But on the whole this looks good to me.
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