Messages in this thread | | | Date | Tue, 22 Apr 2008 08:01:22 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH 1/11] Add generic helpers for arch IPI function calls |
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On Tue, 22 Apr 2008, Jens Axboe wrote: > > > > You forgot to free the "data" here? The waiter must also free the object, > > since now the callee does not. > > The ipi interrupt handler does that, see kfree() in > generic_smp_call_function_single_interrupt() or call_func_data_free() in > generic_smp_call_function_interrupt().
Hell no, it does *not*.
Doing that for the waiting case would be a *huge* bug, since the waiter needs to wait until the flag is clear - and if the waitee free's the allocation, that will never happen.
So the rule *must* be: - waiter frees - ipi interrupt frees non-waiting ones. because anything else cannot work.
And you must have known that, because the code you pointed me to does *not* free the data at all. It just clears the FLAG_WAIT flag:
+ if (data->csd.flags & CSD_FLAG_WAIT) { + smp_wmb(); + data->csd.flags &= ~CSD_FLAG_WAIT; + } else + call_func_data_free(data);
So please think about this some more.
Linus
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