Message ID | 1511989553-16198-1-git-send-email-debmc@linux.vnet.ibm.com (mailing list archive) |
---|---|
State | Superseded |
Headers | show |
Series | [v2] powerpc/powernv: Add queue mechanism for early messages | expand |
Deb McLemore <debmc@linux.vnet.ibm.com> writes: > Problem being solved is when issuing a BMC soft poweroff during IPL, > the poweroff was being lost so the machine would not poweroff. > > Opal messages were being received before the opal-power code > registered its notifiers. > > Alternatives discussed (option #3 was chosen): > > 1 - Have opal_message_init() explicitly call opal_power_control_init() > before it dequeues any OPAL messages (i.e. before we register the > opal-msg IRQ handler). > > 2 - Introduce concept of critical message types and when we register > handlers we track which message types have a registered handler, > then defer the opal-msg IRQ registration until we have a handler > registered for all the critical types. > > 3 - Buffering messages, if we receive a message and do not yet > have a handler for that type, store the message and replay when > a handler for that type is registered. > > Signed-off-by: Deb McLemore <debmc@linux.vnet.ibm.com> > --- > arch/powerpc/platforms/powernv/opal.c | 83 ++++++++++++++++++++++++++++++++--- > 1 file changed, 78 insertions(+), 5 deletions(-) Hi Deb, Sorry for the delay (!) on this one. A couple more comments ... > diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c > index 65c79ec..46d7604 100644 > --- a/arch/powerpc/platforms/powernv/opal.c > +++ b/arch/powerpc/platforms/powernv/opal.c > @@ -238,14 +288,25 @@ machine_early_initcall(powernv, opal_register_exception_handlers); > int opal_message_notifier_register(enum opal_msg_type msg_type, > struct notifier_block *nb) > { > + int ret; > + > if (!nb || msg_type >= OPAL_MSG_TYPE_MAX) { > pr_warning("%s: Invalid arguments, msg_type:%d\n", > __func__, msg_type); > return -EINVAL; > } We still want to take the msg_list_lock around the registration, ie. from here to the end of the function. > - return atomic_notifier_chain_register( > - &opal_msg_notifier_head[msg_type], nb); > + ret = atomic_notifier_chain_register( > + &opal_msg_notifier_head[msg_type], nb); > + > + if (ret) > + return ret; Otherwise a message that arrives here will be delivered before any queued messages, which might be a problem. > + > + /* Replay any queued messages that came in */ > + /* prior to the notifier chain registration */ > + dequeue_replay_msg(msg_type); > + > + return 0; > } > EXPORT_SYMBOL_GPL(opal_message_notifier_register); > > @@ -259,9 +320,21 @@ EXPORT_SYMBOL_GPL(opal_message_notifier_unregister); > > static void opal_message_do_notify(uint32_t msg_type, void *msg) > { > - /* notify subscribers */ > - atomic_notifier_call_chain(&opal_msg_notifier_head[msg_type], > - msg_type, msg); > + unsigned long flags; > + > + spin_lock_irqsave(&msg_list_lock, flags); > + > + if (opal_msg_notifier_head[msg_type].head != NULL) { > + /* notify subscribers */ > + atomic_notifier_call_chain(&opal_msg_notifier_head[msg_type], > + msg_type, msg); > + } else { > + /* Queue up the msg since no notifiers have */ > + /* registered yet for this msg_type */ > + queue_replay_msg(msg); > + } > + > + spin_unlock_irqrestore(&msg_list_lock, flags); I don't think it's actually likely to be a problem, but it would be nice if we didn't have to hold the lock while calling the notifier in the general case. I think we can do that with eg: bool queued = false; spin_lock_irqsave(&msg_list_lock, flags); if (opal_msg_notifier_head[msg_type].head == NULL) { /* * Queue up the msg since no notifiers have registered * yet for this msg_type. */ queue_replay_msg(msg); queued = true; } spin_unlock_irqrestore(&msg_list_lock, flags); if (queued) return; /* notify subscribers */ atomic_notifier_call_chain(&opal_msg_notifier_head[msg_type], msg_type, msg); cheers
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c index 65c79ec..46d7604 100644 --- a/arch/powerpc/platforms/powernv/opal.c +++ b/arch/powerpc/platforms/powernv/opal.c @@ -40,6 +40,16 @@ #include "powernv.h" +#define OPAL_MSG_QUEUE_MAX 16 + +struct opal_msg_node { + struct list_head list; + struct opal_msg msg; +}; + +static DEFINE_SPINLOCK(msg_list_lock); +static LIST_HEAD(msg_list); + /* /sys/firmware/opal */ struct kobject *opal_kobj; @@ -55,6 +65,8 @@ struct mcheck_recoverable_range { u64 recover_addr; }; +static int msg_list_size; + static struct mcheck_recoverable_range *mc_recoverable_range; static int mc_recoverable_range_len; @@ -231,6 +243,44 @@ static int __init opal_register_exception_handlers(void) } machine_early_initcall(powernv, opal_register_exception_handlers); +static void queue_replay_msg(void *msg) +{ + struct opal_msg_node *msg_node; + + if (msg_list_size < OPAL_MSG_QUEUE_MAX) { + msg_node = kzalloc(sizeof(*msg_node), GFP_ATOMIC); + if (msg_node) { + INIT_LIST_HEAD(&msg_node->list); + memcpy(&msg_node->msg, msg, sizeof(struct opal_msg)); + list_add_tail(&msg_node->list, &msg_list); + msg_list_size++; + } else + pr_warn_once("message queue no memory\n"); + + if (msg_list_size >= OPAL_MSG_QUEUE_MAX) + pr_warn_once("message queue full\n"); + } +} + +static void dequeue_replay_msg(enum opal_msg_type msg_type) +{ + struct opal_msg_node *msg_node, *tmp; + unsigned long flags; + + spin_lock_irqsave(&msg_list_lock, flags); + list_for_each_entry_safe(msg_node, tmp, &msg_list, list) { + if (be32_to_cpu(msg_node->msg.msg_type) != msg_type) + continue; + atomic_notifier_call_chain(&opal_msg_notifier_head[msg_type], + msg_type, + &msg_node->msg); + list_del(&msg_node->list); + kfree(msg_node); + msg_list_size--; + } + spin_unlock_irqrestore(&msg_list_lock, flags); +} + /* * Opal message notifier based on message type. Allow subscribers to get * notified for specific messgae type. @@ -238,14 +288,25 @@ machine_early_initcall(powernv, opal_register_exception_handlers); int opal_message_notifier_register(enum opal_msg_type msg_type, struct notifier_block *nb) { + int ret; + if (!nb || msg_type >= OPAL_MSG_TYPE_MAX) { pr_warning("%s: Invalid arguments, msg_type:%d\n", __func__, msg_type); return -EINVAL; } - return atomic_notifier_chain_register( - &opal_msg_notifier_head[msg_type], nb); + ret = atomic_notifier_chain_register( + &opal_msg_notifier_head[msg_type], nb); + + if (ret) + return ret; + + /* Replay any queued messages that came in */ + /* prior to the notifier chain registration */ + dequeue_replay_msg(msg_type); + + return 0; } EXPORT_SYMBOL_GPL(opal_message_notifier_register); @@ -259,9 +320,21 @@ EXPORT_SYMBOL_GPL(opal_message_notifier_unregister); static void opal_message_do_notify(uint32_t msg_type, void *msg) { - /* notify subscribers */ - atomic_notifier_call_chain(&opal_msg_notifier_head[msg_type], - msg_type, msg); + unsigned long flags; + + spin_lock_irqsave(&msg_list_lock, flags); + + if (opal_msg_notifier_head[msg_type].head != NULL) { + /* notify subscribers */ + atomic_notifier_call_chain(&opal_msg_notifier_head[msg_type], + msg_type, msg); + } else { + /* Queue up the msg since no notifiers have */ + /* registered yet for this msg_type */ + queue_replay_msg(msg); + } + + spin_unlock_irqrestore(&msg_list_lock, flags); } static void opal_handle_message(void)
Problem being solved is when issuing a BMC soft poweroff during IPL, the poweroff was being lost so the machine would not poweroff. Opal messages were being received before the opal-power code registered its notifiers. Alternatives discussed (option #3 was chosen): 1 - Have opal_message_init() explicitly call opal_power_control_init() before it dequeues any OPAL messages (i.e. before we register the opal-msg IRQ handler). 2 - Introduce concept of critical message types and when we register handlers we track which message types have a registered handler, then defer the opal-msg IRQ registration until we have a handler registered for all the critical types. 3 - Buffering messages, if we receive a message and do not yet have a handler for that type, store the message and replay when a handler for that type is registered. Signed-off-by: Deb McLemore <debmc@linux.vnet.ibm.com> --- arch/powerpc/platforms/powernv/opal.c | 83 ++++++++++++++++++++++++++++++++--- 1 file changed, 78 insertions(+), 5 deletions(-)