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| author | Rusty Russell <rusty@rustcorp.com.au> | 2013-03-05 10:07:08 +1030 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-03-20 15:03:23 +0000 |
| commit | 4533ed41f0afffa36413ce4f04cc4413e215b321 (patch) | |
| tree | 32dcbd15497cf880953a8907b9b3fe97c3914fd6 /drivers/char | |
| parent | 87c7f521968a1491af48d34a4ea6566485e6426c (diff) | |
| download | lwn-4533ed41f0afffa36413ce4f04cc4413e215b321.tar.gz lwn-4533ed41f0afffa36413ce4f04cc4413e215b321.zip | |
hw_random: make buffer usable in scatterlist.
commit f7f154f1246ccc5a0a7e9ce50932627d60a0c878 upstream.
virtio_rng feeds the randomness buffer handed by the core directly
into the scatterlist, since commit bb347d98079a547e80bd4722dee1de61e4dca0e8.
However, if CONFIG_HW_RANDOM=m, the static buffer isn't a linear address
(at least on most archs). We could fix this in virtio_rng, but it's actually
far easier to just do it in the core as virtio_rng would have to allocate
a buffer every time (it doesn't know how much the core will want to read).
Reported-by: Aurelien Jarno <aurelien@aurel32.net>
Tested-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/hw_random/core.c | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index 1bafb40ec8a2..69ae5972713c 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -40,6 +40,7 @@ #include <linux/init.h> #include <linux/miscdevice.h> #include <linux/delay.h> +#include <linux/slab.h> #include <asm/uaccess.h> @@ -52,8 +53,12 @@ static struct hwrng *current_rng; static LIST_HEAD(rng_list); static DEFINE_MUTEX(rng_mutex); static int data_avail; -static u8 rng_buffer[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES] - __cacheline_aligned; +static u8 *rng_buffer; + +static size_t rng_buffer_size(void) +{ + return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES; +} static inline int hwrng_init(struct hwrng *rng) { @@ -116,7 +121,7 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf, if (!data_avail) { bytes_read = rng_get_data(current_rng, rng_buffer, - sizeof(rng_buffer), + rng_buffer_size(), !(filp->f_flags & O_NONBLOCK)); if (bytes_read < 0) { err = bytes_read; @@ -307,6 +312,14 @@ int hwrng_register(struct hwrng *rng) mutex_lock(&rng_mutex); + /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */ + err = -ENOMEM; + if (!rng_buffer) { + rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL); + if (!rng_buffer) + goto out_unlock; + } + /* Must not register two RNGs with the same name. */ err = -EEXIST; list_for_each_entry(tmp, &rng_list, list) { |