From 57cd52ca4c0ffdb4f48ce7896daa8782aaa8d132 Mon Sep 17 00:00:00 2001 From: Xin LI Date: Sun, 2 Nov 2014 23:30:50 +0000 Subject: [PATCH] - Make sure random_adaptor accesses happen only when 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 --- sys/dev/random/random_adaptors.c | 61 ++++++++++++++++++++------------ 1 file changed, 39 insertions(+), 22 deletions(-) diff --git a/sys/dev/random/random_adaptors.c b/sys/dev/random/random_adaptors.c index 76d2c3e0c3e6..39680a8eba4b 100644 --- a/sys/dev/random/random_adaptors.c +++ b/sys/dev/random/random_adaptors.c @@ -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);