[PATCH 04/11] random: simplify loop in random_read
The loop condition never changes until just before a break, so we
might as well write it as a constant. Also since v2.6.33-rc7~40^2~2
("random: drop weird m_time/a_time manipulation") we don't do
anything after the loop finishes, so the 'break's might as well
return directly. Some other simplifications.
The behavior should be identical except that I've changed a debug
message.
Cc: "Theodore Ts'o"
Signed-off-by: Greg Price
---
drivers/char/random.c | 68 +--
1 file changed, 22 insertions(+), 46 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index d1466c9..85f5fce 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1155,58 +1155,34 @@ void rand_initialize_disk(struct gendisk *disk)
static ssize_t
random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
{
- ssize_t n, retval = 0, count = 0;
+ ssize_t n;
if (nbytes == 0)
return 0;
- while (nbytes > 0) {
- n = nbytes;
- if (n > SEC_XFER_SIZE)
- n = SEC_XFER_SIZE;
-
- DEBUG_ENT("reading %zu bits\n", n*8);
-
- n = extract_entropy_user(_pool, buf, n);
-
- if (n < 0) {
- retval = n;
- break;
- }
-
- DEBUG_ENT("read got %zd bits (%zd still needed)\n",
+ nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE);
+ while (1) {
+ DEBUG_ENT("reading %zu bits\n", nbytes*8);
+ n = extract_entropy_user(_pool, buf, nbytes);
+ if (n < 0)
+ return n;
+ DEBUG_ENT("read got %zd bits (%zd short)\n",
n*8, (nbytes-n)*8);
-
- if (n == 0) {
- if (file->f_flags & O_NONBLOCK) {
- retval = -EAGAIN;
- break;
- }
-
- DEBUG_ENT("sleeping?\n");
-
- wait_event_interruptible(random_read_wait,
- input_pool.entropy_count >=
-random_read_wakeup_thresh);
-
- DEBUG_ENT("awake\n");
-
- if (signal_pending(current)) {
- retval = -ERESTARTSYS;
- break;
- }
-
- continue;
- }
-
- count += n;
- buf += n;
- nbytes -= n;
- break; /* This break makes the device work */
- /* like a named pipe */
+ if (n > 0)
+ return n;
+ /* Pool is (near) empty. Maybe wait and retry. */
+
+ if (file->f_flags & O_NONBLOCK)
+ return -EAGAIN;
+
+ DEBUG_ENT("sleeping?\n");
+ wait_event_interruptible(random_read_wait,
+ input_pool.entropy_count >=
+random_read_wakeup_thresh);
+ DEBUG_ENT("awake\n");
+ if (signal_pending(current))
+ return -ERESTARTSYS;
}
-
- return (count ? count : retval);
}
static ssize_t
--
1.8.3.2
--
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[PATCH 04/11] random: simplify loop in random_read
The loop condition never changes until just before a break, so we
might as well write it as a constant. Also since v2.6.33-rc7~40^2~2
(random: drop weird m_time/a_time manipulation) we don't do
anything after the loop finishes, so the 'break's might as well
return directly. Some other simplifications.
The behavior should be identical except that I've changed a debug
message.
Cc: Theodore Ts'o ty...@mit.edu
Signed-off-by: Greg Price pr...@mit.edu
---
drivers/char/random.c | 68 +--
1 file changed, 22 insertions(+), 46 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index d1466c9..85f5fce 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1155,58 +1155,34 @@ void rand_initialize_disk(struct gendisk *disk)
static ssize_t
random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
{
- ssize_t n, retval = 0, count = 0;
+ ssize_t n;
if (nbytes == 0)
return 0;
- while (nbytes 0) {
- n = nbytes;
- if (n SEC_XFER_SIZE)
- n = SEC_XFER_SIZE;
-
- DEBUG_ENT(reading %zu bits\n, n*8);
-
- n = extract_entropy_user(blocking_pool, buf, n);
-
- if (n 0) {
- retval = n;
- break;
- }
-
- DEBUG_ENT(read got %zd bits (%zd still needed)\n,
+ nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE);
+ while (1) {
+ DEBUG_ENT(reading %zu bits\n, nbytes*8);
+ n = extract_entropy_user(blocking_pool, buf, nbytes);
+ if (n 0)
+ return n;
+ DEBUG_ENT(read got %zd bits (%zd short)\n,
n*8, (nbytes-n)*8);
-
- if (n == 0) {
- if (file-f_flags O_NONBLOCK) {
- retval = -EAGAIN;
- break;
- }
-
- DEBUG_ENT(sleeping?\n);
-
- wait_event_interruptible(random_read_wait,
- input_pool.entropy_count =
-random_read_wakeup_thresh);
-
- DEBUG_ENT(awake\n);
-
- if (signal_pending(current)) {
- retval = -ERESTARTSYS;
- break;
- }
-
- continue;
- }
-
- count += n;
- buf += n;
- nbytes -= n;
- break; /* This break makes the device work */
- /* like a named pipe */
+ if (n 0)
+ return n;
+ /* Pool is (near) empty. Maybe wait and retry. */
+
+ if (file-f_flags O_NONBLOCK)
+ return -EAGAIN;
+
+ DEBUG_ENT(sleeping?\n);
+ wait_event_interruptible(random_read_wait,
+ input_pool.entropy_count =
+random_read_wakeup_thresh);
+ DEBUG_ENT(awake\n);
+ if (signal_pending(current))
+ return -ERESTARTSYS;
}
-
- return (count ? count : retval);
}
static ssize_t
--
1.8.3.2
--
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