Christoph Hellwig <hch@xxxxxx> wrote: > On Mon, Feb 15, 2021 at 10:46:23PM +0000, David Howells wrote: > > The in_softirq() in netfs_rreq_terminated() works fine for the cache being > > on a normal disk, as the completion handlers may get called in softirq > > context, but for an NVMe drive, the completion handler may get called in > > IRQ context. > > > > Fix to use in_interrupt() instead of in_softirq() throughout the read > > helpers, particularly when deciding whether to punt code that might sleep > > off to a worker thread. > > We must not use either check, as they all are unreliable especially > for PREEMPT-RT. Is there a better way to do it? The intent is to process the assessment phase in the calling thread's context if possible rather than bumping over to a worker thread. For synchronous I/O, for example, that's done in the caller's thread. Maybe that's the answer - if it's known to be asynchronous, I have to punt, but otherwise don't have to. David
