On Tue, Nov 15, 2022 at 02:41:35PM -0600, Bjorn Helgaas wrote: > On Tue, Nov 15, 2022 at 12:18:38PM -0800, Ira Weiny wrote: > > On Tue, Nov 15, 2022 at 01:44:24PM -0600, Bjorn Helgaas wrote: > > > and say something more specific than "fix struct"? > > > > How about? > > > > PCI/DOE: Fix initialization of work struct in pci_doe_task > > The importance of this has to do with whether something is on the > stack, so I think something about that would be useful. > > I'm afraid this subject line bike-shedding has made you overlook my > other questions below ... Oh... I see now. > > > > 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]? No. > > > If the current use cases allow a > > > kzalloc(), why not do that now and defer this until it becomes an > > > issue? I do like pci_doe_submit_task() handling this as an internal detail. I'm happy with that if you are. I was just concerned about the restriction of context. Dan suggested this instead of passing a gfp parameter. If you are happy with my original patch I will submit it instead. (With a better one liner.) Thanks again for the review, Ira > > > > > > 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 > > > >
