search for: rng_fillbuf

...e buffer. > > It looks like if another call then happens, and that > other call uses a different buffer, virtio rng > will happily return the data written into the > original buf pointer, confusing the caller. > > Is that right? > Yes. hw_random core uses two bufers: - rng_fillbuf that is used with a blocking access and protected by the reading_mutex. I think this cannot be interrupted by a kill because it's in hwrng_fillfn() and it's kthread. - rng_buffer that is used in rng_dev_read() and can be interrupted (it is also protected by reading_mutex) But if rng_dev_...

...e buffer. > > It looks like if another call then happens, and that > other call uses a different buffer, virtio rng > will happily return the data written into the > original buf pointer, confusing the caller. > > Is that right? > Yes. hw_random core uses two bufers: - rng_fillbuf that is used with a blocking access and protected by the reading_mutex. I think this cannot be interrupted by a kill because it's in hwrng_fillfn() and it's kthread. - rng_buffer that is used in rng_dev_read() and can be interrupted (it is also protected by reading_mutex) But if rng_dev_...

...core.c +++ b/drivers/char/hw_random/core.c @@ -53,7 +53,10 @@ static struct hwrng *current_rng; static struct task_struct *hwrng_fill; static LIST_HEAD(rng_list); +/* Protects rng_list and current_rng */ static DEFINE_MUTEX(rng_mutex); +/* Protects rng read functions, data_avail, rng_buffer and rng_fillbuf */ +static DEFINE_MUTEX(reading_mutex); static int data_avail; static u8 *rng_buffer, *rng_fillbuf; static unsigned short current_quality; @@ -81,7 +84,9 @@ static void add_early_randomness(struct hwrng *rng) unsigned char bytes[16]; int bytes_read; + mutex_lock(&reading_mutex); byte...

...core.c +++ b/drivers/char/hw_random/core.c @@ -53,7 +53,10 @@ static struct hwrng *current_rng; static struct task_struct *hwrng_fill; static LIST_HEAD(rng_list); +/* Protects rng_list and current_rng */ static DEFINE_MUTEX(rng_mutex); +/* Protects rng read functions, data_avail, rng_buffer and rng_fillbuf */ +static DEFINE_MUTEX(reading_mutex); static int data_avail; static u8 *rng_buffer, *rng_fillbuf; static unsigned short current_quality; @@ -81,7 +84,9 @@ static void add_early_randomness(struct hwrng *rng) unsigned char bytes[16]; int bytes_read; + mutex_lock(&reading_mutex); byte...

When I hotunplug a busy virtio-rng device or try to access hwrng attributes in non-smp guest, it gets stuck. My hotplug tests: | test 0: | hotunplug rng device from qemu monitor | | test 1: | guest) # dd if=/dev/hwrng of=/dev/null & | hotunplug rng device from qemu monitor | | test 2: | guest) # dd if=/dev/random of=/dev/null & | hotunplug rng device from qemu monitor | | test

When I hotunplug a busy virtio-rng device or try to access hwrng attributes in non-smp guest, it gets stuck. My hotplug tests: | test 0: | hotunplug rng device from qemu monitor | | test 1: | guest) # dd if=/dev/hwrng of=/dev/null & | hotunplug rng device from qemu monitor | | test 2: | guest) # dd if=/dev/random of=/dev/null & | hotunplug rng device from qemu monitor | | test

When I hotunplug a busy virtio-rng device or try to access hwrng attributes in non-smp guest, it gets stuck. My original was pain, Rusty posted a real fix. This patchset fixed two issue in v1, and tested by my 6+ cases. | test 0: | hotunplug rng device from qemu monitor | | test 1: | guest) # dd if=/dev/hwrng of=/dev/null & | hotunplug rng device from qemu monitor | | test 2: |

When I hotunplug a busy virtio-rng device or try to access hwrng attributes in non-smp guest, it gets stuck. My original was pain, Rusty posted a real fix. This patchset fixed two issue in v1, and tested by my 6+ cases. | test 0: | hotunplug rng device from qemu monitor | | test 1: | guest) # dd if=/dev/hwrng of=/dev/null & | hotunplug rng device from qemu monitor | | test 2: |

Amos Kong <akong at redhat.com> writes: > I started a QEMU (non-smp) guest with one virtio-rng device, and read > random data from /dev/hwrng by dd: > > # dd if=/dev/hwrng of=/dev/null & > > In the same time, if I check hwrng attributes from sysfs by cat: > > # cat /sys/class/misc/hw_random/rng_* > > The cat process always gets stuck with slow backend (5

Amos Kong <akong at redhat.com> writes: > I started a QEMU (non-smp) guest with one virtio-rng device, and read > random data from /dev/hwrng by dd: > > # dd if=/dev/hwrng of=/dev/null & > > In the same time, if I check hwrng attributes from sysfs by cat: > > # cat /sys/class/misc/hw_random/rng_* > > The cat process always gets stuck with slow backend (5

When I hotunplug a busy virtio-rng device or try to access hwrng attributes in non-smp guest, it gets stuck. My hotplug tests: | test 0: | hotunplug rng device from qemu monitor | | test 1: | guest) # dd if=/dev/hwrng of=/dev/null & | hotunplug rng device from qemu monitor | | test 2: | guest) # dd if=/dev/random of=/dev/null & | hotunplug rng device from qemu monitor | | test

When I hotunplug a busy virtio-rng device or try to access hwrng attributes in non-smp guest, it gets stuck. My hotplug tests: | test 0: | hotunplug rng device from qemu monitor | | test 1: | guest) # dd if=/dev/hwrng of=/dev/null & | hotunplug rng device from qemu monitor | | test 2: | guest) # dd if=/dev/random of=/dev/null & | hotunplug rng device from qemu monitor | | test

When I hotunplug a busy virtio-rng device or try to access hwrng attributes in non-smp guest, it gets stuck. My hotplug tests: | test 0: | hotunplug rng device from qemu monitor | | test 1: | guest) # dd if=/dev/hwrng of=/dev/null & | hotunplug rng device from qemu monitor | | test 2: | guest) # dd if=/dev/random of=/dev/null & | hotunplug rng device from qemu monitor | | test

When I hotunplug a busy virtio-rng device or try to access hwrng attributes in non-smp guest, it gets stuck. My hotplug tests: | test 0: | hotunplug rng device from qemu monitor | | test 1: | guest) # dd if=/dev/hwrng of=/dev/null & | hotunplug rng device from qemu monitor | | test 2: | guest) # dd if=/dev/random of=/dev/null & | hotunplug rng device from qemu monitor | | test

...ens, and that > > other call uses a different buffer, virtio rng > > will happily return the data written into the > > original buf pointer, confusing the caller. > > > > Is that right? > > > > Yes. > > hw_random core uses two bufers: > > - rng_fillbuf that is used with a blocking access and protected by the > reading_mutex. I think this cannot be interrupted by a kill because it's > in hwrng_fillfn() and it's kthread. > > - rng_buffer that is used in rng_dev_read() and can be interrupted (it > is also protected by readin...

...hw_random/core.c > index dc9092a1075d..b4a21e9521cf 100644 > --- a/drivers/char/hw_random/core.c > +++ b/drivers/char/hw_random/core.c > @@ -60,6 +60,7 @@ static DEFINE_MUTEX(rng_mutex); > static DEFINE_MUTEX(reading_mutex); > static int data_avail; > static u8 *rng_buffer, *rng_fillbuf; > +static DECLARE_WAIT_QUEUE_HEAD(rng_done); > static unsigned short current_quality; > static unsigned short default_quality; /* = 0; default to "off" */ > > @@ -98,6 +99,7 @@ static inline void cleanup_rng(struct kref *kref) > > if (rng->cleanup) >...

...hw_random/core.c > index dc9092a1075d..b4a21e9521cf 100644 > --- a/drivers/char/hw_random/core.c > +++ b/drivers/char/hw_random/core.c > @@ -60,6 +60,7 @@ static DEFINE_MUTEX(rng_mutex); > static DEFINE_MUTEX(reading_mutex); > static int data_avail; > static u8 *rng_buffer, *rng_fillbuf; > +static DECLARE_WAIT_QUEUE_HEAD(rng_done); > static unsigned short current_quality; > static unsigned short default_quality; /* = 0; default to "off" */ > > @@ -98,6 +99,7 @@ static inline void cleanup_rng(struct kref *kref) > > if (rng->cleanup) >...

On 11/08/2020 14:53, Martin Wilck wrote: > On Tue, 2020-08-11 at 14:39 +0200, Laurent Vivier wrote: >> On 11/08/2020 14:22, Martin Wilck wrote: >>> On Tue, 2020-08-11 at 14:02 +0200, Laurent Vivier wrote: >>>>>> drivers/char/hw_random/virtio-rng.c | 14 ++++++++++++++ >>>>>> 1 file changed, 14 insertions(+) >>>>>>

On 11/08/2020 14:53, Martin Wilck wrote: > On Tue, 2020-08-11 at 14:39 +0200, Laurent Vivier wrote: >> On 11/08/2020 14:22, Martin Wilck wrote: >>> On Tue, 2020-08-11 at 14:02 +0200, Laurent Vivier wrote: >>>>>> drivers/char/hw_random/virtio-rng.c | 14 ++++++++++++++ >>>>>> 1 file changed, 14 insertions(+) >>>>>>

...n(void *unused) > long rc; > > while (!kthread_should_stop()) { > - if (!current_rng) > + struct hwrng *rng; > + > + rng = get_current_rng(); > + if (IS_ERR(rng) || !rng) > break; > mutex_lock(&reading_mutex); > - rc = rng_get_data(current_rng, rng_fillbuf, > + rc = rng_get_data(rng, rng_fillbuf, > rng_buffer_size(), 1); > mutex_unlock(&reading_mutex); > + put_rng(rng); > if (rc <= 0) { > pr_warn("hwrng: no data available\n"); > msleep_interruptible(10000); > @@ -423,14 +475,13 @@ int hw...