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Code Issues Releases Activity

- Make sure random_adaptor accesses happen only when

Browse Source 
random_adaptors_lock is held.
 - Use sx_sleep instead of tsleep in read and write path to allow
   another thread that registers a new random adapter when waiting.
   Assert that random_adaptor is not NULL after reacquiring the lock.
 - Capture EINTR/ERESTART from sx_sleep to allow the blocking cycle be
   stopped when user requests so, while there also make short
   read/write's return 0.
 - Move M_WAITOK allocations out of lock scope.

In collobration with:	kib, markm, ian, jilles
Reviewed by:	kib, markm
Approved by:	so
This commit is contained in:
Xin LI 2014-11-02 23:30:50 +00:00
parent 824fc46089
commit 57cd52ca4c
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=273997
1 changed files with 39 additions and 22 deletions
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61
sys/dev/random/random_adaptors.c
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@ -171,9 +171,8 @@ random_adaptor_register(const char *name, struct random_adaptor *ra)
sx_xlock(&random_adaptors_lock);
LIST_INSERT_HEAD(&random_adaptors_list, rra, rra_entries);
random_adaptor_choose();
sx_xunlock(&random_adaptors_lock);
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s", __func__));
sx_xunlock(&random_adaptors_lock);
}
void
@ -182,9 +181,9 @@ random_adaptor_deregister(const char *name)
struct random_adaptors *rra;
KASSERT(name != NULL, ("invalid input to %s", __func__));
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s", __func__));
sx_xlock(&random_adaptors_lock);
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s", __func__));
LIST_FOREACH(rra, &random_adaptors_list, rra_entries)
if (strcmp(rra->rra_name, name) == 0) {
LIST_REMOVE(rra, rra_entries);
@ -208,23 +207,28 @@ random_adaptor_read(struct cdev *dev __unused, struct uio *uio, int flags)
printf("random: %s %ld\n", __func__, uio->uio_resid);
#endif
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s", __func__));
random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK);
sx_slock(&random_adaptors_lock);
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s", __func__));
/* Let the entropy source do any pre-read setup. */
(random_adaptor->ra_read)(NULL, 0);
/* (Un)Blocking logic */
error = 0;
while (!random_adaptor->ra_seeded()) {
while (!random_adaptor->ra_seeded() && error == 0) {
if (flags & O_NONBLOCK) {
error = EWOULDBLOCK;
break;
}
/* Sleep instead of going into a spin-frenzy */
tsleep(&random_adaptor, PUSER | PCATCH, "block", hz/10);
error = sx_sleep(&random_adaptor, &random_adaptors_lock,
PUSER | PCATCH, "randrd", hz/10);
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s",
__func__));
/* keep tapping away at the pre-read until we seed/unblock. */
(random_adaptor->ra_read)(NULL, 0);
@ -241,12 +245,10 @@ random_adaptor_read(struct cdev *dev __unused, struct uio *uio, int flags)
mtx_unlock(&random_read_rate_mtx);
if (!error) {
if (error == 0) {
nbytes = uio->uio_resid;
/* The actual read */
random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK);
while (uio->uio_resid && !error) {
c = MIN(uio->uio_resid, PAGE_SIZE);
(random_adaptor->ra_read)(random_buf, c);
@ -256,11 +258,15 @@ random_adaptor_read(struct cdev *dev __unused, struct uio *uio, int flags)
/* Let the entropy source do any post-read cleanup. */
(random_adaptor->ra_read)(NULL, 1);
free(random_buf, M_ENTROPY);
}
if (nbytes != uio->uio_resid && (error == ERESTART ||
error == EINTR) )
error = 0; /* Return partial read, not error. */
}
sx_sunlock(&random_adaptors_lock);
free(random_buf, M_ENTROPY);
return (error);
}
@ -269,6 +275,8 @@ random_adaptor_read_rate(void)
{
int ret;
sx_assert(&random_adaptors_lock, SA_LOCKED);
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s", __func__));
mtx_lock(&random_read_rate_mtx);
@ -287,18 +295,20 @@ random_adaptor_write(struct cdev *dev __unused, struct uio *uio, int flags __unu
{
int c, error = 0;
void *random_buf;
ssize_t nbytes;
#ifdef RANDOM_DEBUG
printf("random: %s %zd\n", __func__, uio->uio_resid);
#endif
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s", __func__));
random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK);
sx_slock(&random_adaptors_lock);
random_buf = malloc(PAGE_SIZE, M_ENTROPY, M_WAITOK);
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s", __func__));
while (uio->uio_resid > 0) {
nbytes = uio->uio_resid;
while (uio->uio_resid > 0 && error == 0) {
c = MIN(uio->uio_resid, PAGE_SIZE);
error = uiomove(random_buf, c, uio);
if (error)
@ -306,13 +316,20 @@ random_adaptor_write(struct cdev *dev __unused, struct uio *uio, int flags __unu
(random_adaptor->ra_write)(random_buf, c);
/* Introduce an annoying delay to stop swamping */
tsleep(&random_adaptor, PUSER | PCATCH, "block", hz/10);
error = sx_sleep(&random_adaptor, &random_adaptors_lock,
PUSER | PCATCH, "randwr", hz/10);
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s",
__func__));
}
free(random_buf, M_ENTROPY);
sx_sunlock(&random_adaptors_lock);
if (nbytes != uio->uio_resid && (error == ERESTART ||
error == EINTR) )
error = 0; /* Partial write, not error. */
free(random_buf, M_ENTROPY);
return (error);
}
@ -325,10 +342,10 @@ random_adaptor_poll(struct cdev *dev __unused, int events, struct thread *td __u
printf("random: %s\n", __func__);
#endif
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s", __func__));
sx_slock(&random_adaptors_lock);
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s", __func__));
if (events & (POLLIN | POLLRDNORM)) {
if (random_adaptor->ra_seeded())
events &= (POLLIN | POLLRDNORM);
@ -382,9 +399,9 @@ random_sysctl_active_adaptor_handler(SYSCTL_HANDLER_ARGS)
struct sbuf sbuf;
int error;
sx_slock(&random_adaptors_lock);
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s", __func__));
sx_slock(&random_adaptors_lock);
sbuf_new_for_sysctl(&sbuf, NULL, 16, req);
LIST_FOREACH(rra, &random_adaptors_list, rra_entries)
if (rra->rra_ra == random_adaptor) {
@ -454,9 +471,9 @@ static void
random_adaptors_seed(void *unused __unused)
{
sx_slock(&random_adaptors_lock);
KASSERT(random_adaptor != NULL, ("No active random adaptor in %s", __func__));
sx_slock(&random_adaptors_lock);
random_adaptor->ra_reseed();
sx_sunlock(&random_adaptors_lock);