Hi Ira, Can you fix the subject to follow capitalization convention (use "git log --oneline") and say something more specific than "fix struct"? 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. I'm not really a fan of passing a parameter to say "this struct is on the stack" because that seems kind of error-prone and I don't know what the consequence of getting it wrong would be. Sounds like it *could* be some memory corruption or reading garbage data that would be hard to debug. Do we have cases today where pci_doe_submit_task() can't do the kzalloc() as in your patch at [3]? If the current use cases allow a kzalloc(), why not do that now and defer this until it becomes an issue? Bjorn > [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 [3] https://lore.kernel.org/linux-cxl/Y2AnKB88ALYm9c5L@iweiny-desk3/ > Cc: Bjorn Helgaas <helgaas@xxxxxxxxxx> > Reported-by: Gregory Price <gregory.price@xxxxxxxxxxxx> > Reported-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> > Suggested-by: Dan Williams <dan.j.williams@xxxxxxxxx> > Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx> > --- > drivers/cxl/core/pci.c | 2 ++ > drivers/pci/doe.c | 14 ++++++++++++-- > include/linux/pci-doe.h | 8 +++++--- > 3 files changed, 19 insertions(+), 5 deletions(-) > > diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c > index 9240df53ed87..a19c1fa0e2f4 100644 > --- a/drivers/cxl/core/pci.c > +++ b/drivers/cxl/core/pci.c > @@ -525,6 +525,7 @@ static int cxl_cdat_get_length(struct device *dev, > DECLARE_CDAT_DOE_TASK(CDAT_DOE_REQ(0), t); > int rc; > > + pci_doe_init_task(cdat_doe, &t.task, true); > rc = pci_doe_submit_task(cdat_doe, &t.task); > if (rc < 0) { > dev_err(dev, "DOE submit failed: %d", rc); > @@ -554,6 +555,7 @@ static int cxl_cdat_read_table(struct device *dev, > u32 *entry; > int rc; > > + pci_doe_init_task(cdat_doe, &t.task, true); > rc = pci_doe_submit_task(cdat_doe, &t.task); > if (rc < 0) { > dev_err(dev, "DOE submit failed: %d", rc); > diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c > index e402f05068a5..cabeae4ae955 100644 > --- a/drivers/pci/doe.c > +++ b/drivers/pci/doe.c > @@ -319,6 +319,7 @@ static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid, > }; > int rc; > > + pci_doe_init_task(doe_mb, &task, true); > rc = pci_doe_submit_task(doe_mb, &task); > if (rc < 0) > return rc; > @@ -495,6 +496,14 @@ bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type) > } > EXPORT_SYMBOL_GPL(pci_doe_supports_prot); > > +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, > + bool onstack) > +{ > + task->doe_mb = doe_mb; > + __INIT_WORK(&task->work, doe_statemachine_work, onstack); > +} > +EXPORT_SYMBOL_GPL(pci_doe_init_task); > + > /** > * pci_doe_submit_task() - Submit a task to be processed by the state machine > * > @@ -517,6 +526,9 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) > if (!pci_doe_supports_prot(doe_mb, task->prot.vid, task->prot.type)) > return -EINVAL; > > + if (WARN_ON_ONCE(task->work.func != doe_statemachine_work)) > + return -EINVAL; > + > /* > * DOE requests must be a whole number of DW and the response needs to > * be big enough for at least 1 DW > @@ -528,8 +540,6 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task) > if (test_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags)) > return -EIO; > > - task->doe_mb = doe_mb; > - INIT_WORK(&task->work, doe_statemachine_work); > queue_work(doe_mb->work_queue, &task->work); > return 0; > } > diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h > index ed9b4df792b8..457fc0e53d64 100644 > --- a/include/linux/pci-doe.h > +++ b/include/linux/pci-doe.h > @@ -31,8 +31,8 @@ struct pci_doe_mb; > * @rv: Return value. Length of received response or error (bytes) > * @complete: Called when task is complete > * @private: Private data for the consumer > - * @work: Used internally by the mailbox > - * @doe_mb: Used internally by the mailbox > + * @work: Used internally by the mailbox [see pci_doe_init_task()] > + * @doe_mb: Used internally by the mailbox [see pci_doe_init_task()] > * > * The payload sizes and rv are specified in bytes with the following > * restrictions concerning the protocol. > @@ -53,7 +53,7 @@ struct pci_doe_task { > void (*complete)(struct pci_doe_task *task); > void *private; > > - /* No need for the user to initialize these fields */ > + /* Call pci_doe_init_task() for these */ > struct work_struct work; > struct pci_doe_mb *doe_mb; > }; > @@ -72,6 +72,8 @@ struct pci_doe_task { > > struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset); > bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type); > +void pci_doe_init_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task, > + bool onstack); > int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task); > > #endif > > base-commit: 30a0b95b1335e12efef89dd78518ed3e4a71a763 > -- > 2.37.2 >
