Messages in this thread Patch in this message | | | Date | Fri, 2 Apr 2004 10:33:27 -0800 | From | "Randy.Dunlap" <> | Subject | Re: BUG_ON(!cpus_equal(cpumask, tmp)); |
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On Thu, 01 Apr 2004 12:38:40 +0100 Andy Whitcroft wrote:
| --On 01 April 2004 10:34 +0530 Srivatsa Vaddagiri <vatsa@in.ibm.com> wrote: | | > Hmm ..Doesn't it need to drop tlbstate_lock before returning? | > The second lock should be call_lock? | | Yes and Yes. I don't know how Andrew copes with 300 odd patches. | I don't seem to be able to keep track of the versions on 3 of them? | Seems I sent out an old version. Doh. Explicit version numbers | from now on. | | Below is tested version of the patch. If anyone can reproduce the | issue I would be interested in knowing if this passes a reboot on | that system. | | Apologies for the confusion. And thanks for reviewing!
This version works well, thank you. Without it I still see the BUG_ON() in smp.c (line 359).
I noted a few comments corrections and style changes below. Want a patch for them instead?
| @@ -367,16 +365,24 @@ static void flush_tlb_others(cpumask_t c | * detected by the NMI watchdog. | */ | spin_lock(&tlbstate_lock); | + | + /* Subtle, mask the request mask with the currently online cpu's. | + * Sample this under the lock; cpus in the the middle of going x.x | + * offline will wait until there is noone in this critical section | + * before disabling IPI handling. */ | + cpus_and(tmp, cpumask, cpu_online_map); | + if(cpus_empty(tmp)) if (cpus_empty(tmp)) | + goto out_unlock;
| @@ -527,6 +531,15 @@ int smp_call_function (void (*func) (voi | atomic_set(&data.finished, 0); | | spin_lock(&call_lock); | + | + /* Subtle, get the current number of online cpus. | + * Sample this under the lock; cpus in the the middle of going x.x | + * offline will wait until there is noone in this critical section | + * before disabling IPI handling. */
| @@ -551,6 +565,20 @@ static void stop_this_cpu (void * dummy) | * Remove this CPU: | */ | cpu_clear(smp_processor_id(), cpu_online_map); | + | + /* Subtle, IPI users assume that they will be able to get IPI's | + * though to the cpus listed in cpu_online_map. To ensure this through | + * we add the requirement that they check cpu_online_map within | + * the IPI critical sections. Here we remove ourselves from the | + * map, then ensure that all other cpus have left the relevant | + * critical sections since the change. We do this by aquiring acquiring | + * the relevant section locks, if we have them none else is in noone | + * them. Once this is done we can go offline. */
-- ~Randy (Again. Sometimes I think ln -s /usr/src/linux/.config .signature) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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