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McKenney wrote: > On Tue, Sep 08, 2026 at 11:29:31AM -0400, Mathieu Desnoyers wrote: >> On 2026-09-08 11:24, Bradley Morgan wrote: >>> On 8 September 2026 16:22:14 BST, Mathieu Desnoyers >>> wrote: >>>> When hazptr_acquire loads a NULL pointer, it sets: >>>> >>>> - slot_item->slot.addr = NULL, >>>> - slot_item->ctx.ctx = ctx >>>> - ctx->slot = slot >>>> >>>> And it returns NULL. >>>> >>>> Then hazptr_detach is called on this ctx, it will act on the ctx as if >>>> needed to be promoted to backup slot, even though it has a NULL addr. >>>> >>>> Looking at what hazptr_note_context_switch() does before promoting >>>> to backup slot, it checks for a NULL slot->addr, which is exactly >>>> what is missing from hazptr_detach. >>>> >>>> With this in place there would be no need to explicitly check the >>>> hazptr_acquire() return value before calling hazptr_detach(). >>>> >>>> hazptr_release() has a early return check for NULL addr as well, so it >>>> makes sense that detach does an early return (no-op) similarly. >>>> >>> >>> You shall kill me for this!! >>> >>> Could you perhaps do a splat in ze commit description pls? >> >> The splat is available at the "Closes" URL below. I'm not sure whether >> we should duplicate this verbose information ? >> >> Paul ? > > I am fine either way, as long as the information is reasonably easily > accessible. Which is the case either way. ;-) Then I favor a concise commit message, leaving the splat details to the "Closes" link. Feel free to pick up this patch for testing. Thank you! Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com