aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJeff Dike <jdike@addtoit.com>2008-04-29 01:03:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-29 08:06:25 -0700
commit9a6f70bbed4e8b72dd340812d7c606bfd5e00b47 (patch)
tree55158b087275b1848b5f0ad4e58eb2a2d47016c8
parentadc782dae6c4c0f6fb679a48a544cfbcd79ae3dc (diff)
downloadlinux-linaro-9a6f70bbed4e8b72dd340812d7c606bfd5e00b47.tar.gz
random: add async notification support to /dev/random
Add async notification support to /dev/random. A little test case is below. Without this patch, you get: $ ./async-random Drained the pool Found more randomness With it, you get: $ ./async-random Drained the pool SIGIO Found more randomness #include <stdio.h> #include <stdlib.h> #include <signal.h> #include <errno.h> #include <fcntl.h> static void handler(int sig) { printf("SIGIO\n"); } int main(int argc, char **argv) { int fd, n, err, flags; if(signal(SIGIO, handler) < 0){ perror("setting SIGIO handler"); exit(1); } fd = open("/dev/random", O_RDONLY); if(fd < 0){ perror("open"); exit(1); } flags = fcntl(fd, F_GETFL); if (flags < 0){ perror("getting flags"); exit(1); } flags |= O_NONBLOCK; if (fcntl(fd, F_SETFL, flags) < 0){ perror("setting flags"); exit(1); } while((err = read(fd, &n, sizeof(n))) > 0) ; if(err == 0){ printf("random returned 0\n"); exit(1); } else if(errno != EAGAIN){ perror("read"); exit(1); } flags |= O_ASYNC; if (fcntl(fd, F_SETFL, flags) < 0){ perror("setting flags"); exit(1); } if (fcntl(fd, F_SETOWN, getpid()) < 0) { perror("Setting SIGIO"); exit(1); } printf("Drained the pool\n"); read(fd, &n, sizeof(n)); printf("Found more randomness\n"); return(0); } Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Matt Mackall <mpm@selenic.com> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/char/random.c24
1 files changed, 22 insertions, 2 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 2faeef28c20..0cf98bd4f2d 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -370,6 +370,7 @@ static struct poolinfo {
*/
static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
+static struct fasync_struct *fasync;
#if 0
static int debug;
@@ -533,8 +534,11 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
r->entropy_count = r->poolinfo->POOLBITS;
/* should we wake readers? */
- if (r == &input_pool && r->entropy_count >= random_read_wakeup_thresh)
+ if (r == &input_pool &&
+ r->entropy_count >= random_read_wakeup_thresh) {
wake_up_interruptible(&random_read_wait);
+ kill_fasync(&fasync, SIGIO, POLL_IN);
+ }
spin_unlock_irqrestore(&r->lock, flags);
}
@@ -742,8 +746,10 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
else
r->entropy_count = reserved;
- if (r->entropy_count < random_write_wakeup_thresh)
+ if (r->entropy_count < random_write_wakeup_thresh) {
wake_up_interruptible(&random_write_wait);
+ kill_fasync(&fasync, SIGIO, POLL_OUT);
+ }
}
DEBUG_ENT("debiting %d entropy credits from %s%s\n",
@@ -1100,17 +1106,31 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
}
}
+static int random_fasync(int fd, struct file *filp, int on)
+{
+ return fasync_helper(fd, filp, on, &fasync);
+}
+
+static int random_release(struct inode *inode, struct file *filp)
+{
+ return fasync_helper(-1, filp, 0, &fasync);
+}
+
const struct file_operations random_fops = {
.read = random_read,
.write = random_write,
.poll = random_poll,
.unlocked_ioctl = random_ioctl,
+ .fasync = random_fasync,
+ .release = random_release,
};
const struct file_operations urandom_fops = {
.read = urandom_read,
.write = random_write,
.unlocked_ioctl = random_ioctl,
+ .fasync = random_fasync,
+ .release = random_release,
};
/***************************************************************