On Wed, Nov 16, 2022 at 11:09:39AM +0100, Lukas Wunner wrote: > On Mon, Nov 14, 2022 at 05:19:43PM -0800, ira.weiny@xxxxxxxxx wrote: > > From: Ira Weiny <ira.weiny@xxxxxxxxx> > > > > The callers of pci_doe_submit_task() allocate the pci_doe_task on the > > stack. This causes the work structure to be allocated on the stack > > without pci_doe_submit_task() knowing. Work item initialization needs > > to be done with either INIT_WORK_ONSTACK() or INIT_WORK() depending on > > how the work item is allocated. > > > > 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. > > > > Compromise with an intermediate step to initialize the task struct with > > a new call pci_doe_init_task() which must be called prior to submit > > task. > > > > [1] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@xxxxxxxxxx/T/#m88a7f50dcce52f30c8bf5c3dcc06fa9843b54a2d > > [2] https://lore.kernel.org/linux-cxl/20221014151045.24781-1-Jonathan.Cameron@xxxxxxxxxx/T/#m63c636c5135f304480370924f4d03c00357be667 > > We have object_is_on_stack(), included from <linux/sched/task_stack.h>. > > So you could just autosense in pci_doe_submit_task() whether > pci_doe_task is on the stack and call the appropriate INIT_WORK > variant. Nifty, I had no idea object_is_on_stack() existed, thank you! I wonder if there's an opportunity to use object_is_on_stack() somewhere in the INIT_WORK() path to find usage mistakes. Adding it in pci_doe_submit_task() would add some complexity, so I'm not sure whether it's worth adding it unless we actually have uses for both cases. Bjorn
