==> Regarding RE: [patch] aio: fix buggy put_ioctx call in aio_complete; "Chen, Kenneth W" <[EMAIL PROTECTED]> adds:
kenneth.w.chen> [EMAIL PROTECTED] wrote on Thursday, December 21, 2006 8:56 kenneth.w.chen> AM I think I'm going to abandon this whole synchronize kenneth.w.chen> thing and going to put the wake up call inside ioctx_lock kenneth.w.chen> spin lock along with the other patch you mentioned above in kenneth.w.chen> the waiter path. On top of that, I have another patch kenneth.w.chen> attempts to perform wake-up only when the waiter can truly kenneth.w.chen> proceed in aio_read_evt so dribbling I/O completion doesn't kenneth.w.chen> inefficiently waking up waiter too frequently and only to kenneth.w.chen> have waiter put back to sleep again. I will dig that up and kenneth.w.chen> experiment. >> In the mean time, can't we simply take the context lock in >> wait_for_all_aios? Unless I missed something, I think that will address >> the reference count problem. kenneth.w.chen> Take ioctx_lock is one part, the other part is to move kenneth.w.chen> spin_unlock_irqrestore(&ctx->ctx_lock, flags); kenneth.w.chen> in aio_complete all the way down to the end of the kenneth.w.chen> function, after wakeup and put_ioctx. But then the ref kenneth.w.chen> counting on ioctx in aio_complete path is Meaningless, kenneth.w.chen> which is the thing I'm trying to remove. OK, right. But are we simply papering over the real problem? Earlier in this thread, you stated: > flush_workqueue() is not allowed to be called in the softirq context. > However, aio_complete() called from I/O interrupt can potentially call > put_ioctx with last ref count on ioctx and trigger a bug warning. It > is simply incorrect to perform ioctx freeing from aio_complete. But how do we end up with the last reference to the ioctx in the aio completion path? That's a question I haven't seen answered. -Jeff - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
