Messages in this thread Patch in this message | | | Date | Thu, 7 Nov 2013 18:58:40 -0500 | From | Greg Price <> | Subject | [PATCH 04/11] random: simplify loop in random_read |
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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" <tytso@mit.edu> Signed-off-by: Greg Price <price@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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