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| author |   Rusty Russell <rusty@rustcorp.com.au> | 2014-12-08 16:50:37 +0800 |
|---|---|---|
| committer |   Herbert Xu <herbert@gondor.apana.org.au> | 2014-12-22 23:02:39 +1100 |
| commit | 3a2c0ba5ad00c018c0bef39a2224aca950aa33f2 (patch) | |
| tree | 1fbf69fb820c0fa2e6050f8caaecff424c73bd8d /include/linux/hw_random.h | |
| parent | hwrng: move some code out mutex_lock for avoiding underlying deadlock (diff) | |
| download | linux-dev-3a2c0ba5ad00c018c0bef39a2224aca950aa33f2.tar.xz linux-dev-3a2c0ba5ad00c018c0bef39a2224aca950aa33f2.zip | |
hwrng: use reference counts on each struct hwrng.
current_rng holds one reference, and we bump it every time we want
to do a read from it.
This means we only hold the rng_mutex to grab or drop a reference,
so accessing /sys/devices/virtual/misc/hw_random/rng_current doesn't
block on read of /dev/hwrng.
Using a kref is overkill (we're always under the rng_mutex), but
a standard pattern.
This also solves the problem that the hwrng_fillfn thread was
accessing current_rng without a lock, which could change (eg. to NULL)
underneath it.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Amos Kong <akong@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'include/linux/hw_random.h')
| -rw-r--r-- | include/linux/hw_random.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/hw_random.h b/include/linux/hw_random.h index 914bb08cd738..c212e71ea886 100644 --- a/include/linux/hw_random.h +++ b/include/linux/hw_random.h @@ -14,6 +14,7 @@ #include <linux/types.h> #include <linux/list.h> +#include <linux/kref.h> /** * struct hwrng - Hardware Random Number Generator driver @@ -44,6 +45,7 @@ struct hwrng { /* internal. */ struct list_head list; + struct kref ref; }; /** Register a new Hardware Random Number Generator driver. */ |