Now with Thomas added to cc for real. On Tue, Nov 22, 2022 at 06:13:09PM +0100, Lukas Wunner wrote: > [+cc Thomas Gleixner, author of dc186ad741c1] > > On Fri, Nov 18, 2022 at 09:20:38AM +0000, David Laight wrote: > > > From: ira.weiny@xxxxxxxxx > > > Sent: 18 November 2022 00:05 > > > > > > Work item initialization needs to be done with either > > > INIT_WORK_ONSTACK() or INIT_WORK() depending on how the work item is > > > allocated. > > > > > > The callers of pci_doe_submit_task() allocate struct pci_doe_task on the > > > stack and pci_doe_submit_task() incorrectly used INIT_WORK(). > > > > > > Jonathan suggested creating doe task allocation macros such as > > > DECLARE_CDAT_DOE_TASK_ONSTACK().[1] The issue with this is the work > > > function is not known to the callers and must be initialized correctly. > > > > > > A follow up suggestion was to have an internal 'pci_doe_work' item > > > allocated by pci_doe_submit_task().[2] This requires an allocation which > > > could restrict the context where tasks are used. > > > > > > Another idea was to have an intermediate step to initialize the task > > > struct with a new call.[3] This added a lot of complexity. > > > > > > Lukas pointed out that object_is_on_stack() is available to detect this > > > automatically. > > > > > > Use object_is_on_stack() to determine the correct init work function to > > > call. > > > > This is all a bit strange. > > The 'onstack' flag is needed for the diagnostic check: > > is_on_stack = object_is_on_stack(addr); > > if (is_on_stack == onstack) > > return; > > pr_warn(...); > > WARN_ON(1); > > > > So setting the flag to the location of the buffer just subverts the check. > > It that is sane there ought to be a proper way to do it. > > If object_is_on_stack() is sufficient to check whether a struct > is on the stack or not, why doesn't __init_work() use it to > auto-detect whether to call debug_object_init_on_stack() or > debug_object_init()? > > Forcing developers to use a specific initializer for something > that can be auto-detected is akin to treating them like kids > and telling them "You didn't say the magic word." > > What's the point? > > Thanks, > > Lukas
