On 24/04/2020 21:26, Jason Gunthorpe wrote:
> On Fri, Apr 24, 2020 at 06:25:54PM +0300, Gal Pressman wrote:
>> On 24/04/2020 17:59, Jason Gunthorpe wrote:
>>> On Mon, Apr 20, 2020 at 09:22:12AM +0300, Gal Pressman wrote:
>>>> Add a new stat that counts mmap failures, which might help when
>>>> debugging different issues.
>>>>
>>>> Reviewed-by: Firas JahJah <firasj@xxxxxxxxxx>
>>>> Reviewed-by: Yossi Leybovich <sleybo@xxxxxxxxxx>
>>>> Signed-off-by: Gal Pressman <galpress@xxxxxxxxxx>
>>>> drivers/infiniband/hw/efa/efa.h | 3 ++-
>>>> drivers/infiniband/hw/efa/efa_verbs.c | 9 +++++++--
>>>> 2 files changed, 9 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/infiniband/hw/efa/efa.h b/drivers/infiniband/hw/efa/efa.h
>>>> index aa7396a1588a..77c9ff798117 100644
>>>> +++ b/drivers/infiniband/hw/efa/efa.h
>>>> @@ -1,6 +1,6 @@
>>>> /* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
>>>> /*
>>>> - * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All rights reserved.
>>>> + * Copyright 2018-2020 Amazon.com, Inc. or its affiliates. All rights reserved.
>>>> */
>>>>
>>>> #ifndef _EFA_H_
>>>> @@ -40,6 +40,7 @@ struct efa_sw_stats {
>>>> atomic64_t reg_mr_err;
>>>> atomic64_t alloc_ucontext_err;
>>>> atomic64_t create_ah_err;
>>>> + atomic64_t mmap_err;
>>>> };
>>>>
>>>> /* Don't use anything other than atomic64 */
>>>> diff --git a/drivers/infiniband/hw/efa/efa_verbs.c b/drivers/infiniband/hw/efa/efa_verbs.c
>>>> index b555845d6c14..75eef1ec2474 100644
>>>> +++ b/drivers/infiniband/hw/efa/efa_verbs.c
>>>> @@ -44,7 +44,8 @@ struct efa_user_mmap_entry {
>>>> op(EFA_CREATE_CQ_ERR, "create_cq_err") \
>>>> op(EFA_REG_MR_ERR, "reg_mr_err") \
>>>> op(EFA_ALLOC_UCONTEXT_ERR, "alloc_ucontext_err") \
>>>> - op(EFA_CREATE_AH_ERR, "create_ah_err")
>>>> + op(EFA_CREATE_AH_ERR, "create_ah_err") \
>>>> + op(EFA_MMAP_ERR, "mmap_err")
>>>>
>>>> #define EFA_STATS_ENUM(ename, name) ename,
>>>> #define EFA_STATS_STR(ename, name) [ename] = name,
>>>> @@ -1569,6 +1570,7 @@ static int __efa_mmap(struct efa_dev *dev, struct efa_ucontext *ucontext,
>>>> ibdev_dbg(&dev->ibdev,
>>>> "pgoff[%#lx] does not have valid entry\n",
>>>> vma->vm_pgoff);
>>>> + atomic64_inc(&dev->stats.sw_stats.mmap_err);
>>>> return -EINVAL;
>>>> }
>>>> entry = to_emmap(rdma_entry);
>>>> @@ -1604,12 +1606,14 @@ static int __efa_mmap(struct efa_dev *dev, struct efa_ucontext *ucontext,
>>>> err = -EINVAL;
>>>> }
>>>>
>>>> - if (err)
>>>> + if (err) {
>>>> ibdev_dbg(
>>>> &dev->ibdev,
>>>> "Couldn't mmap address[%#llx] length[%#zx] mmap_flag[%d] err[%d]\n",
>>>> entry->address, rdma_entry->npages * PAGE_SIZE,
>>>> entry->mmap_flag, err);
>>>> + atomic64_inc(&dev->stats.sw_stats.mmap_err);
>>>
>>> Really? Isn't this something that is only possible with a buggy
>>> rdma-core provider? Why count it?
>>
>> Though unlikely, it could happen, otherwise this error flow wouldn't exist in
>> the first place.
>>
>> If for some reason a customer app steps on a bug we're not aware of, this
>> counter could serve as a red flag.
>
> But there are lots of cases where a buggy provider can cause error
> exits, why choose this one to count against all the others?
It's not one against all others, most if not all of our userspace facing API
error flows have a similar counter.
And TBH, I think that the mmap flow is quite convoluted with the cookie response
from the crate verb, so it deserves a counter IMO.
