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Message-ID: <20200203115039.GF2260@nanopsycho>
Date: Mon, 3 Feb 2020 12:50:39 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: Yunsheng Lin <linyunsheng@...wei.com>
Cc: Jacob Keller <jacob.e.keller@...el.com>, netdev@...r.kernel.org,
valex@...lanox.com, lihong.yang@...el.com
Subject: Re: [PATCH 03/15] devlink: add operation to take an immediate
snapshot
Mon, Feb 03, 2020 at 09:19:23AM CET, linyunsheng@...wei.com wrote:
>On 2020/1/31 6:58, Jacob Keller wrote:
>> Add a new devlink command, DEVLINK_CMD_REGION_TAKE_SNAPSHOT. This
>> command is intended to enable userspace to request an immediate snapshot
>> of a region.
>>
>> Regions can enable support for requestable snapshots by implementing the
>> snapshot callback function in the region's devlink_region_ops structure.
>>
>> Implementations of this function callback should capture an immediate
>> copy of the data and return it and its destructor in the function
>> parameters. The core devlink code will generate a snapshot ID and create
>> the new snapshot while holding the devlink instance lock.
>
>Does we need a new devlink command to clear the snapshot created by
>DEVLINK_CMD_REGION_TAKE_SNAPSHOT?
>
>It seems the snapshot of a region is only destroyed when unloading
>the driver.
There is existing command to handle this:
devlink region del DEV/REGION snapshot SNAPSHOT_ID
>
>>
>> Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
>> ---
>> .../networking/devlink/devlink-region.rst | 9 +++-
>> include/net/devlink.h | 7 +++
>> include/uapi/linux/devlink.h | 2 +
>> net/core/devlink.c | 46 +++++++++++++++++++
>> 4 files changed, 62 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/networking/devlink/devlink-region.rst b/Documentation/networking/devlink/devlink-region.rst
>> index 1a7683e7acb2..262249e6c3fc 100644
>> --- a/Documentation/networking/devlink/devlink-region.rst
>> +++ b/Documentation/networking/devlink/devlink-region.rst
>> @@ -20,6 +20,11 @@ address regions that are otherwise inaccessible to the user.
>> Regions may also be used to provide an additional way to debug complex error
>> states, but see also :doc:`devlink-health`
>>
>> +Regions may optionally support capturing a snapshot on demand via the
>> +``DEVLINK_CMD_REGION_TAKE_SNAPSHOT`` netlink message. A driver wishing to
>> +allow requested snapshots must implement the ``.snapshot`` callback for the
>> +region in its ``devlink_region_ops`` structure.
>> +
>> example usage
>> -------------
>>
>> @@ -40,8 +45,8 @@ example usage
>> # Delete a snapshot using:
>> $ devlink region del pci/0000:00:05.0/cr-space snapshot 1
>>
>> - # Trigger (request) a snapshot be taken:
>> - $ devlink region trigger pci/0000:00:05.0/cr-space
>> + # Request an immediate snapshot, if supported by the region
>> + $ devlink region snapshot pci/0000:00:05.0/cr-space
>>
>> # Dump a snapshot:
>> $ devlink region dump pci/0000:00:05.0/fw-health snapshot 1
>> diff --git a/include/net/devlink.h b/include/net/devlink.h
>> index 4a0baa6903cb..63e954241404 100644
>> --- a/include/net/devlink.h
>> +++ b/include/net/devlink.h
>> @@ -498,9 +498,16 @@ typedef void devlink_snapshot_data_dest_t(const void *data);
>> /**
>> * struct devlink_region_ops - Region operations
>> * @name: region name
>> + * @snapshot: callback to request an immediate snapshot. On success,
>> + * the data and destructor variables must be updated. The function
>> + * will be called while the devlink instance lock is held.
>> */
>> struct devlink_region_ops {
>> const char *name;
>> + int (*snapshot)(struct devlink *devlink,
>> + struct netlink_ext_ack *extack,
>> + u8 **data,
>> + devlink_snapshot_data_dest_t **destructor);
>> };
>>
>> struct devlink_fmsg;
>> diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
>> index ae37fd4d194a..46643c4320b9 100644
>> --- a/include/uapi/linux/devlink.h
>> +++ b/include/uapi/linux/devlink.h
>> @@ -117,6 +117,8 @@ enum devlink_command {
>> DEVLINK_CMD_TRAP_GROUP_NEW,
>> DEVLINK_CMD_TRAP_GROUP_DEL,
>>
>> + DEVLINK_CMD_REGION_TAKE_SNAPSHOT,
>> +
>> /* add new commands above here */
>> __DEVLINK_CMD_MAX,
>> DEVLINK_CMD_MAX = __DEVLINK_CMD_MAX - 1
>> diff --git a/net/core/devlink.c b/net/core/devlink.c
>> index faf4f4c5c539..574008c536fa 100644
>> --- a/net/core/devlink.c
>> +++ b/net/core/devlink.c
>> @@ -4109,6 +4109,45 @@ static int devlink_nl_cmd_region_read_dumpit(struct sk_buff *skb,
>> return err;
>> }
>>
>> +static int devlink_nl_cmd_region_take_snapshot(struct sk_buff *skb,
>> + struct genl_info *info)
>> +{
>> + struct devlink *devlink = info->user_ptr[0];
>> + devlink_snapshot_data_dest_t *destructor;
>> + struct devlink_region *region;
>> + const char *region_name;
>> + u32 snapshot_id;
>> + u8 *data;
>> + int err;
>> +
>> + if (!info->attrs[DEVLINK_ATTR_REGION_NAME]) {
>> + NL_SET_ERR_MSG_MOD(info->extack, "No region name provided");
>> + return -EINVAL;
>> + }
>> +
>> + region_name = nla_data(info->attrs[DEVLINK_ATTR_REGION_NAME]);
>> + region = devlink_region_get_by_name(devlink, region_name);
>> + if (!region) {
>> + NL_SET_ERR_MSG_MOD(info->extack,
>> + "The requested region does not exist");
>> + return -EINVAL;
>> + }
>> +
>> + if (!region->ops->snapshot) {
>> + NL_SET_ERR_MSG_MOD(info->extack,
>> + "The requested region does not support taking an immediate snapshot");
>> + return -EOPNOTSUPP;
>> + }
>> +
>> + err = region->ops->snapshot(devlink, info->extack, &data, &destructor);
>> + if (err)
>> + return err;
>> +
>> + snapshot_id = devlink_region_snapshot_id_get_locked(devlink);
>> + return devlink_region_snapshot_create_locked(region, data, snapshot_id,
>> + destructor);
>> +}
>> +
>> struct devlink_info_req {
>> struct sk_buff *msg;
>> };
>> @@ -6249,6 +6288,13 @@ static const struct genl_ops devlink_nl_ops[] = {
>> .flags = GENL_ADMIN_PERM,
>> .internal_flags = DEVLINK_NL_FLAG_NEED_DEVLINK,
>> },
>> + {
>> + .cmd = DEVLINK_CMD_REGION_TAKE_SNAPSHOT,
>> + .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
>> + .doit = devlink_nl_cmd_region_take_snapshot,
>> + .flags = GENL_ADMIN_PERM,
>> + .internal_flags = DEVLINK_NL_FLAG_NEED_DEVLINK,
>> + },
>> {
>> .cmd = DEVLINK_CMD_INFO_GET,
>> .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
>>
>
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