I am looking at it.
On Tue, May 6, 2014 at 12:50 PM, Ben Pfaff <b...@nicira.com> wrote:
> Commit 2a3fb0aa3c (lacp: Don't lock potentially uninitialized mutex in
> lacp_status().) fixed one bug related to acquiring the file scope 'mutex'
> without initializing it. However, there was at least one other, in
> lacp_unixctl_show(). One could just fix that one problem, but that leaves
> the possibility that I might have missed one or two more. This commit
> fixes the problem for good, by adding a helper that initializes the mutex
> and then acquires it.
>
> It's not entirely clear why 'mutex' is a recursive mutex. I think that it
> might be just because of the callback in lacp_run(). An alternate fix,
> therefore, would be to eliminate the callback and therefore the need for
> runtime initialization of the mutex.
>
> Bug #1245659.
> Reported-by: Jeffrey Merrick <jmerr...@vmware.com>
> Signed-off-by: Ben Pfaff <b...@nicira.com>
> ---
> lib/lacp.c | 76
> +++++++++++++++++++++++++++++++++++-------------------------
> 1 file changed, 44 insertions(+), 32 deletions(-)
>
> diff --git a/lib/lacp.c b/lib/lacp.c
> index 49ae5e5..0d30e51 100644
> --- a/lib/lacp.c
> +++ b/lib/lacp.c
> @@ -203,25 +203,37 @@ lacp_init(void)
> lacp_unixctl_show, NULL);
> }
>
> -/* Creates a LACP object. */
> -struct lacp *
> -lacp_create(void) OVS_EXCLUDED(mutex)
> +static void
> +lacp_lock(void) OVS_ACQUIRES(mutex)
> {
> static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
> - struct lacp *lacp;
>
> if (ovsthread_once_start(&once)) {
> ovs_mutex_init_recursive(&mutex);
> ovsthread_once_done(&once);
> }
> + ovs_mutex_lock(&mutex);
> +}
> +
> +static void
> +lacp_unlock(void) OVS_RELEASES(mutex)
> +{
> + ovs_mutex_unlock(&mutex);
> +}
> +
> +/* Creates a LACP object. */
> +struct lacp *
> +lacp_create(void) OVS_EXCLUDED(mutex)
> +{
> + struct lacp *lacp;
>
> lacp = xzalloc(sizeof *lacp);
> hmap_init(&lacp->slaves);
> ovs_refcount_init(&lacp->ref_cnt);
>
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> list_push_back(all_lacps, &lacp->node);
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> return lacp;
> }
>
> @@ -242,7 +254,7 @@ lacp_unref(struct lacp *lacp) OVS_EXCLUDED(mutex)
> if (lacp && ovs_refcount_unref(&lacp->ref_cnt) == 1) {
> struct slave *slave, *next;
>
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> HMAP_FOR_EACH_SAFE (slave, next, node, &lacp->slaves) {
> slave_destroy(slave);
> }
> @@ -251,7 +263,7 @@ lacp_unref(struct lacp *lacp) OVS_EXCLUDED(mutex)
> list_remove(&lacp->node);
> free(lacp->name);
> free(lacp);
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> }
> }
>
> @@ -262,7 +274,7 @@ lacp_configure(struct lacp *lacp, const struct
> lacp_settings *s)
> {
> ovs_assert(!eth_addr_is_zero(s->id));
>
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> if (!lacp->name || strcmp(s->name, lacp->name)) {
> free(lacp->name);
> lacp->name = xstrdup(s->name);
> @@ -283,7 +295,7 @@ lacp_configure(struct lacp *lacp, const struct
> lacp_settings *s)
> lacp->update = true;
> }
>
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> }
>
> /* Returns true if 'lacp' is configured in active mode, false if 'lacp' is
> @@ -292,9 +304,9 @@ bool
> lacp_is_active(const struct lacp *lacp) OVS_EXCLUDED(mutex)
> {
> bool ret;
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> ret = lacp->active;
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> return ret;
> }
>
> @@ -311,7 +323,7 @@ lacp_process_packet(struct lacp *lacp, const void *slave_,
> long long int tx_rate;
> struct slave *slave;
>
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> slave = slave_lookup(lacp, slave_);
> if (!slave) {
> goto out;
> @@ -338,7 +350,7 @@ lacp_process_packet(struct lacp *lacp, const void *slave_,
> }
>
> out:
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> }
>
> /* Returns the lacp_status of the given 'lacp' object (which may be NULL). */
> @@ -348,9 +360,9 @@ lacp_status(const struct lacp *lacp) OVS_EXCLUDED(mutex)
> if (lacp) {
> enum lacp_status ret;
>
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> ret = lacp->negotiated ? LACP_NEGOTIATED : LACP_CONFIGURED;
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> return ret;
> } else {
> /* Don't take 'mutex'. It might not even be initialized, since we
> @@ -369,7 +381,7 @@ lacp_slave_register(struct lacp *lacp, void *slave_,
> {
> struct slave *slave;
>
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> slave = slave_lookup(lacp, slave_);
> if (!slave) {
> slave = xzalloc(sizeof *slave);
> @@ -401,7 +413,7 @@ lacp_slave_register(struct lacp *lacp, void *slave_,
> slave_set_expired(slave);
> }
> }
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> }
>
> /* Unregisters 'slave_' with 'lacp'. */
> @@ -411,13 +423,13 @@ lacp_slave_unregister(struct lacp *lacp, const void
> *slave_)
> {
> struct slave *slave;
>
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> slave = slave_lookup(lacp, slave_);
> if (slave) {
> slave_destroy(slave);
> lacp->update = true;
> }
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> }
>
> /* This function should be called whenever the carrier status of 'slave_' has
> @@ -431,7 +443,7 @@ lacp_slave_carrier_changed(const struct lacp *lacp, const
> void *slave_)
> return;
> }
>
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> slave = slave_lookup(lacp, slave_);
> if (!slave) {
> goto out;
> @@ -442,7 +454,7 @@ lacp_slave_carrier_changed(const struct lacp *lacp, const
> void *slave_)
> }
>
> out:
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> }
>
> static bool
> @@ -466,10 +478,10 @@ lacp_slave_may_enable(const struct lacp *lacp, const
> void *slave_)
> struct slave *slave;
> bool ret;
>
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> slave = slave_lookup(lacp, slave_);
> ret = slave ? slave_may_enable__(slave) : false;
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> return ret;
> } else {
> return true;
> @@ -486,10 +498,10 @@ lacp_slave_is_current(const struct lacp *lacp, const
> void *slave_)
> struct slave *slave;
> bool ret;
>
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> slave = slave_lookup(lacp, slave_);
> ret = slave ? slave->status != LACP_DEFAULTED : false;
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> return ret;
> }
>
> @@ -499,7 +511,7 @@ lacp_run(struct lacp *lacp, lacp_send_pdu *send_pdu)
> OVS_EXCLUDED(mutex)
> {
> struct slave *slave;
>
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> HMAP_FOR_EACH (slave, node, &lacp->slaves) {
> if (timer_expired(&slave->rx)) {
> enum slave_status old_status = slave->status;
> @@ -545,7 +557,7 @@ lacp_run(struct lacp *lacp, lacp_send_pdu *send_pdu)
> OVS_EXCLUDED(mutex)
> seq_change(connectivity_seq_get());
> }
> }
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> }
>
> /* Causes poll_block() to wake up when lacp_run() needs to be called again.
> */
> @@ -554,7 +566,7 @@ lacp_wait(struct lacp *lacp) OVS_EXCLUDED(mutex)
> {
> struct slave *slave;
>
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> HMAP_FOR_EACH (slave, node, &lacp->slaves) {
> if (slave_may_tx(slave)) {
> timer_wait(&slave->tx);
> @@ -564,7 +576,7 @@ lacp_wait(struct lacp *lacp) OVS_EXCLUDED(mutex)
> timer_wait(&slave->rx);
> }
> }
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> }
>
> /* Static Helpers. */
> @@ -946,7 +958,7 @@ lacp_unixctl_show(struct unixctl_conn *conn, int argc,
> const char *argv[],
> struct ds ds = DS_EMPTY_INITIALIZER;
> struct lacp *lacp;
>
> - ovs_mutex_lock(&mutex);
> + lacp_lock();
> if (argc > 1) {
> lacp = lacp_find(argv[1]);
> if (!lacp) {
> @@ -964,5 +976,5 @@ lacp_unixctl_show(struct unixctl_conn *conn, int argc,
> const char *argv[],
> ds_destroy(&ds);
>
> out:
> - ovs_mutex_unlock(&mutex);
> + lacp_unlock();
> }
> --
> 1.7.10.4
>
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