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Date: Thu, 16 May 2019 13:53:53 +0200
From: Jiri Pirko <jiri@...nulli.us>
To: Aya Levin <ayal@...lanox.com>
Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Eran Ben Elisha <eranbe@...lanox.com>,
Saeed Mahameed <saeedm@...lanox.com>,
Jiri Pirko <jiri@...lanox.com>
Subject: Re: [PATCH net-next RFC] Dump SW SQ context as part of tx reporter
Thu, May 16, 2019 at 10:49:54AM CEST, ayal@...lanox.com wrote:
>
>
>On 5/14/2019 3:07 PM, Jiri Pirko wrote:
>> Sun, May 12, 2019 at 10:37:35AM CEST, ayal@...lanox.com wrote:
>>>
>>>
>>> On 5/9/2019 11:23 AM, Jiri Pirko wrote:
>>>> Tue, May 07, 2019 at 02:58:32PM CEST, ayal@...lanox.com wrote:
>>>>>
>>>>>
>>>>> On 5/7/2019 3:41 PM, Jiri Pirko wrote:
>>>>>> Mon, Apr 29, 2019 at 04:17:39PM CEST, ayal@...lanox.com wrote:
>>>>>>> TX reporter reports an error on two scenarios:
>>>>>>> - TX timeout on a specific tx queue
>>>>>>> - TX completion error on a specific send queue
>>>>>>> Prior to this patch, no dump data was supported by the tx reporter. This
>>>>>>> patch adds support for SW data dump of the related SQ context. The dump
>>>>>>> is simply the SQ's raw memory snapshot taken right after the error was
>>>>>>> reported, before any recovery procedure was launched. With this
>>>>>>> approach, no maintenance is needed as the driver fetch the actual data
>>>>>>> according to the layout on which the SQ was compiled with. By providing
>>>>>>> a SW context, one can easily debug error on a given SQ.
>>>>>>>
>>>>>>> In order to offline translate the raw memory into a human readable
>>>>>>> format, the user can use some out-of-kernel scripts which receives as an
>>>>>>> input the following:
>>>>>>> - Object raw memory
>>>>>>> - Driver object compiled with debug info (can be taken/generated at any time from the machine)
>>>>>>> - Object name
>>>>>>>
>>>>>>> An example of such script output can be seen below.
>>>>>>> Note: the script is not offered as part of this patch as it do not
>>>>>>> belong to the kernel, I just described it in order to grasp the general
>>>>>>> idea of how/what can be fetched from SW dump via devlink health.
>>>>>>>
>>>>>>> The output of the SW dump can be extracted by devlink health command:
>>>>>>> $ sudo devlink health dump show pci/0000:00:0b.0 reporter tx.
>>>>>>> mlx5e_txqsq: sqn: 6336
>>>>>>> memory:
>>>>>>> 00 00 00 00 00 00 00 00
>>>>>>> 01 00 00 00 00 00 00 00
>>>>>>> 00 00 00 00 00 00 00 00
>>>>>>> 45 f4 88 cb 09 00 00 00
>>>>>>> 00 00 00 00 00 00 00 00
>>>>>>> 00 00 00 00 00 00 00 00
>>>>>>> c0 ff ff ff 1f 00 00 00
>>>>>>> f8 18 1e 89 81 88 ff ff
>>>>>>> ...
>>>>>>>
>>>>>>> script output below, with struct members names and actual values:
>>>>>>>
>>>>>>> struct mlx5e_txqsq {
>>>>>>> short unsigned int cc 0x5 ;
>>>>>>> unsigned int dma_fifo_cc 0x5 ;
>>>>>>> struct net_dim {
>>>>>>> unsigned char state 0x1 ;
>>>>>>> struct net_dim_stats {
>>>>>>> int ppms 0x0 ;
>>>>>>> int bpms 0x0 ;
>>>>>>> int epms 0x0 ;
>>>>>>> } prev_stats;
>>>>>>> struct net_dim_sample {
>>>>>>> long long int time 0x90766ef9d ;
>>>>>>> unsigned int pkt_ctr 0x0 ;
>>>>>>> unsigned int byte_ctr 0x0 ;
>>>>>>> short unsigned int event_ctr 0x0 ;
>>>>>>> } start_sample;
>>>>>>> struct work_struct {
>>>>>>> struct {
>>>>>>> long int counter 0x1fffffffc0 ;
>>>>>>> } data;
>>>>>>> struct list_head {
>>>>>>> struct list_head * next 0xffff8881b08998f8 ;
>>>>>>> struct list_head * prev 0xffff8881b08998f8 ;
>>>>>>> } entry;
>>>>>>> void (*func)(struct work_struct *) 0xffffffffa02d0e30 ;
>>>>>>> } work;
>>>>>>> unsigned char profile_ix 0x60 ;
>>>>>>> unsigned char mode 0x72 ;
>>>>>>> unsigned char tune_state 0x35 ;
>>>>>>> unsigned char steps_right 0xa0 ;
>>>>>>> unsigned char steps_left 0xff ;
>>>>>>> unsigned char tired 0xff ;
>>>>>>> } dim;
>>>>>>> short unsigned int pc 0x0 ;
>>>>>>> unsigned int dma_fifo_pc 0x0 ;
>>>>>>> struct mlx5e_cq {
>>>>>>> struct mlx5_cqwq {
>>>>>>> struct mlx5_frag_buf_ctrl {
>>>>>>> struct mlx5_buf_list * frags 0x500000005 ;
>>>>>>> unsigned int sz_m1 0x0 ;
>>>>>>> short unsigned int frag_sz_m1 0x0 ;
>>>>>>> short unsigned int strides_offset 0x0 ;
>>>>>>> unsigned char log_sz 0x0 ;
>>>>>>> unsigned char log_stride 0x0 ;
>>>>>>> unsigned char log_frag_strides 0x0 ;
>>>>>>> } fbc;
>>>>>>> __be32 * db 0x0 ;
>>>>>>> unsigned int cc 0x0 ;
>>>>>>> } wq;
>>>>>>> short unsigned int event_ctr 0x0 ;
>>>>>>> struct napi_struct * napi 0x0 ;
>>>>>>> struct mlx5_core_cq {
>>>>>>> unsigned int cqn 0x0 ;
>>>>>>> int cqe_sz 0x0 ;
>>>>>>> __be32 * set_ci_db 0xffff8881b1aa4988 ;
>>>>>>> __be32 * arm_db 0x3f000003ff ;
>>>>>>> struct mlx5_uars_page * uar 0x6060a ;
>>>>>>> struct refcount_struct {
>>>>>>> struct {
>>>>>>> int counter 0xa1814500 ;
>>>>>>> } refs;
>>>>>>> } refcount;
>>>>>>> struct completion {
>>>>>>> unsigned int done 0x5 ;
>>>>>>> struct wait_queue_head {
>>>>>>> struct spinlock {
>>>>>>> union {
>>>>>>> struct raw_spinlock {
>>>>>>> struct qspinlock {
>>>>>>> union {
>>>>>>> struct {
>>>>>>> int counter 0x5 ;
>>>>>>> } val;
>>>>>>> struct {
>>>>>>> unsigned char locked 0x5 ;
>>>>>>> unsigned char pending 0x0 ;
>>>>>>> } ;
>>>>>>> struct {
>>>>>>> short unsigned int locked_pending 0x5 ;
>>>>>>> short unsigned int tail 0x0 ;
>>>>>>> } ;
>>>>>>> } ;
>>>>>>> } raw_lock;
>>>>>>> } rlock;
>>>>>>> } ;
>>>>>>> } lock;
>>>>>>> struct list_head {
>>>>>>> struct list_head * next 0xffff8881b089bb88 ;
>>>>>>> struct list_head * prev 0x4000000c0a ;
>>>>>>> } head;
>>>>>>> } wait;
>>>>>>> } free;
>>>>>>> unsigned int vector 0xa1814500 ;
>>>>>>> unsigned int irqn 0xffff8881 ;
>>>>>>> void (*comp)(struct mlx5_core_cq *) 0xffff8881a1814504 ;
>>>>>>> void (*event)(struct mlx5_core_cq *, enum mlx5_event) 0xffff8881a2cdea08 ;
>>>>>>> unsigned int cons_index 0x1 ;
>>>>>>> unsigned int arm_sn 0x0 ;
>>>>>>> struct mlx5_rsc_debug * dbg 0x0 ;
>>>>>>> int pid 0x0 ;
>>>>>>> struct {
>>>>>>> struct list_head {
>>>>>>> struct list_head * next 0xffffffff ;
>>>>>>> struct list_head * prev 0xffffffffffffffff ;
>>>>>>> } list;
>>>>>>> void (*comp)(struct mlx5_core_cq *) 0xffffffffa0356940 ;
>>>>>>> void * priv 0x0 ;
>>>>>>> } tasklet_ctx;
>>>>>>> int reset_notify_added 0x0 ;
>>>>>>> struct list_head {
>>>>>>> struct list_head * next 0xffffffffa0300700 ;
>>>>>>> struct list_head * prev 0xd ;
>>>>>>> } reset_notify;
>>>>>>> struct mlx5_eq_comp * eq 0x0 ;
>>>>>>> short unsigned int uid 0x9a70 ;
>>>>>>> } mcq;
>>>>>>> struct mlx5e_channel * channel 0xffff8881b0899a70 ;
>>>>>>> struct mlx5_core_dev * mdev 0x4800000001 ;
>>>>>>> struct mlx5_wq_ctrl {
>>>>>>> struct mlx5_core_dev * mdev 0xffffffffa02d5350 ;
>>>>>>> struct mlx5_frag_buf {
>>>>>>> struct mlx5_buf_list * frags 0xffffffffa02d5460 ;
>>>>>>> int npages 0x0 ;
>>>>>>> int size 0x5 ;
>>>>>>> unsigned char page_shift 0x8 ;
>>>>>>> } buf;
>>>>>>> struct mlx5_db {
>>>>>>> __be32 * db 0x1c6 ;
>>>>>>> union {
>>>>>>> struct mlx5_db_pgdir * pgdir 0x0 ;
>>>>>>> struct mlx5_ib_user_db_page * user_page 0x0 ;
>>>>>>> } u;
>>>>>>> long long unsigned int dma 0xffff8881b0899ab0 ;
>>>>>>> int index 0x0 ;
>>>>>>> } db;
>>>>>>> } wq_ctrl;
>>>>>>> } cq;
>>>>>>> struct mlx5_wq_cyc {
>>>>>>> struct mlx5_frag_buf_ctrl {
>>>>>>> struct mlx5_buf_list * frags 0xffff8881a7600160 ;
>>>>>>> unsigned int sz_m1 0xa7600160 ;
>>>>>>> short unsigned int frag_sz_m1 0x8881 ;
>>>>>>> short unsigned int strides_offset 0xffff ;
>>>>>>> unsigned char log_sz 0x88 ;
>>>>>>> unsigned char log_stride 0x49 ;
>>>>>>> unsigned char log_frag_strides 0xaa ;
>>>>>>> } fbc;
>>>>>>> __be32 * db 0x1000000000010 ;
>>>>>>> short unsigned int sz 0xc ;
>>>>>>> short unsigned int wqe_ctr 0x0 ;
>>>>>>> short unsigned int cur_sz 0x0 ;
>>>>>>> } wq;
>>>>>>> unsigned int dma_fifo_mask 0xa1814500 ;
>>>>>>> struct mlx5e_sq_stats * stats 0xffff8881a33a0348 ;
>>>>>>> struct {
>>>>>>> struct mlx5e_sq_dma * dma_fifo 0x1a1814500 ;
>>>>>>> struct mlx5e_tx_wqe_info * wqe_info 0x14 ;
>>>>>>> } db;
>>>>>>> void * uar_map 0x0 ;
>>>>>>> struct netdev_queue * txq 0x0 ;
>>>>>>> unsigned int sqn 0x18c0 ;
>>>>>>> unsigned char min_inline_mode 0x0 ;
>>>>>>> struct device * pdev 0x0 ;
>>>>>>> unsigned int mkey_be 0x0 ;
>>>>>>> long unsigned int state 0x0 ;
>>>>>>> struct hwtstamp_config * tstamp 0x0 ;
>>>>>>> struct mlx5_clock * clock 0xffff8881b1aa6f88 ;
>>>>>>> struct mlx5_wq_ctrl {
>>>>>>> struct mlx5_core_dev * mdev 0x3f000003ff ;
>>>>>>> struct mlx5_frag_buf {
>>>>>>> struct mlx5_buf_list * frags 0x6060a ;
>>>>>>> int npages 0xa1814604 ;
>>>>>>> int size 0xffff8881 ;
>>>>>>> unsigned char page_shift 0x0 ;
>>>>>>> } buf;
>>>>>>> struct mlx5_db {
>>>>>>> __be32 * db 0xfff ;
>>>>>>> union {
>>>>>>> struct mlx5_db_pgdir * pgdir 0x0 ;
>>>>>>> struct mlx5_ib_user_db_page * user_page 0x0 ;
>>>>>>> } u;
>>>>>>> long long unsigned int dma 0xffff888188440000 ;
>>>>>>> int index 0x8b074000 ;
>>>>>>> } db;
>>>>>>> } wq_ctrl;
>>>>>>> struct mlx5e_channel * channel 0xffffc9000010d800 ;
>>>>>>> int txq_ix 0xa0020180 ;
>>>>>>> unsigned int rate_limit 0xffff8881 ;
>>>>>>> struct work_struct {
>>>>>>> struct {
>>>>>>> long int counter 0x1000018c0 ;
>>>>>>> } data;
>>>>>>> struct list_head {
>>>>>>> struct list_head * next 0xffff8881c32b68e8 ;
>>>>>>> struct list_head * prev 0x800 ;
>>>>>>> } entry;
>>>>>>> void (*func)(struct work_struct *) 0x9 ;
>>>>>>> } recover_work;
>>>>>>> } ;
>>>>>>
>>>>>> I don't get it. You are dumping live kernel memory? There are already
>>>>>> facilities to do that in place. Why to replicate it?
>>>>> I am dumping the driver's memory under a lock so I can ensure it's
>>>>> consistency (as appose to /dev/mem)
>>>>> vmcore cannot be taken from a live kernel (without crashing).
>>>>> I need the memory's snapshot right after the error from the driver's
>>>>> context.
>>>>
>>>> Got it. However, this sounds like a generic problem not specific to
>>>> nic drivers. How other subsystems resolve this (if they do at all)?
>>>>
>>>>
>>> Correct, this is a suggested debugging solution for a generic problem:
>>> enabling the user of a run time memory snapshot for kernel modules (at a
>>> given error event). My research shows that other subsystems deal with
>>> errors either by panicking (too much) or by debug/log prints (too little).
>>> This solution is (a) low in maintenance (b) consistent in memory (c) has
>>> small performance impact (d) use an existing infra-structure between the
>>> kernel module and the user space.
>>
>> I'm still convinced that dumping kernel memory over devlink health dump
>> is a good idea :/
>>
>>
>>> It might be ported to other subsystems using their own user-space vs.
>>> kernel tools. Regardless of how the memory output was generated to the
>>> user, the parsing script can work on it.
>>
>> Could you share the script? How is it going to be distributed?
>I thought that the script should be in a available on Mellanox website.
:(
>The script is still pending review but I will be happy to share it when
>its ready.
>>
>>
>>>
>>>>
>>>>> Which other tools do you mean?
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> Signed-off-by: Aya Levin <ayal@...lanox.com>
>>>>>>> ---
>>>>>>> .../ethernet/mellanox/mlx5/core/en/reporter_tx.c | 100 +++++++++++++++++++++
>>>>>>> 1 file changed, 100 insertions(+)
>>>>>>>
>>>>>>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/reporter_tx.c b/drivers/net/ethernet/mellanox/mlx5/core/en/reporter_tx.c
>>>>>>> index 476dd97f7f2f..8a39f5525e57 100644
>>>>>>> --- a/drivers/net/ethernet/mellanox/mlx5/core/en/reporter_tx.c
>>>>>>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/reporter_tx.c
>>>>>>> @@ -9,6 +9,7 @@
>>>>>>>
>>>>>>> struct mlx5e_tx_err_ctx {
>>>>>>> int (*recover)(struct mlx5e_txqsq *sq);
>>>>>>> + int (*dump)(struct mlx5e_txqsq *sq);
>>>>>>> struct mlx5e_txqsq *sq;
>>>>>>> };
>>>>>>>
>>>>>>> @@ -281,10 +282,109 @@ static int mlx5e_tx_reporter_diagnose(struct devlink_health_reporter *reporter,
>>>>>>> return err;
>>>>>>> }
>>>>>>>
>>>>>>> +static int mlx5e_tx_reporter_sw_dump_from_ctx(struct mlx5e_priv *priv,
>>>>>>> + struct mlx5e_txqsq *sq,
>>>>>>> + struct devlink_fmsg *fmsg)
>>>>>>> +{
>>>>>>> + u64 *ptr = (u64 *)sq;
>>>>>>> + int copy, err;
>>>>>>> + int i = 0;
>>>>>>> +
>>>>>>> + if (!test_bit(MLX5E_STATE_OPENED, &priv->state))
>>>>>>> + return 0;
>>>>>>> +
>>>>>>> + err = devlink_fmsg_pair_nest_start(fmsg, "mlx5e_txqsq");
>>>>>>> + if (err)
>>>>>>> + return err;
>>>>>>> +
>>>>>>> + err = devlink_fmsg_obj_nest_start(fmsg);
>>>>>>> + if (err)
>>>>>>> + return err;
>>>>>>> +
>>>>>>> + err = devlink_fmsg_arr_pair_nest_start(fmsg, "memory");
>>>>>>> + if (err)
>>>>>>> + return err;
>>>>>>> +
>>>>>>> + while (i < sizeof(struct mlx5e_txqsq)) {
>>>>>>> + copy = sizeof(u64);
>>>>>>> +
>>>>>>> + if (i + copy > sizeof(struct mlx5e_txqsq))
>>>>>>> + copy = sizeof(struct mlx5e_txqsq) - i;
>>>>>>> +
>>>>>>> + err = devlink_fmsg_binary_put(fmsg, ptr, copy);
>>>>>>> + if (err)
>>>>>>> + return err;
>>>>>>> + ptr++;
>>>>>>> + i += copy;
>>>>>>> + }
>>>>>>> +
>>>>>>> + err = devlink_fmsg_arr_pair_nest_end(fmsg);
>>>>>>> + if (err)
>>>>>>> + return err;
>>>>>>> +
>>>>>>> + err = devlink_fmsg_obj_nest_end(fmsg);
>>>>>>> + if (err)
>>>>>>> + return err;
>>>>>>> +
>>>>>>> + err = devlink_fmsg_pair_nest_end(fmsg);
>>>>>>> +
>>>>>>> + return err;
>>>>>>> +}
>>>>>>> +
>>>>>>> +static int mlx5e_tx_reporter_sw_dump_all(struct mlx5e_priv *priv,
>>>>>>> + struct devlink_fmsg *fmsg)
>>>>>>> +{
>>>>>>> + int i, err = 0;
>>>>>>> +
>>>>>>> + mutex_lock(&priv->state_lock);
>>>>>>> +
>>>>>>> + if (!test_bit(MLX5E_STATE_OPENED, &priv->state))
>>>>>>> + goto unlock;
>>>>>>> +
>>>>>>> + err = devlink_fmsg_arr_pair_nest_start(fmsg, "SQs");
>>>>>>> + if (err)
>>>>>>> + goto unlock;
>>>>>>> +
>>>>>>> + for (i = 0; i < priv->channels.num * priv->channels.params.num_tc;
>>>>>>> + i++) {
>>>>>>> + err = devlink_fmsg_obj_nest_start(fmsg);
>>>>>>> + if (err)
>>>>>>> + goto unlock;
>>>>>>> +
>>>>>>> + err = mlx5e_tx_reporter_sw_dump_from_ctx(priv, priv->txq2sq[i],
>>>>>>> + fmsg);
>>>>>>> + if (err)
>>>>>>> + goto unlock;
>>>>>>> +
>>>>>>> + err = devlink_fmsg_pair_nest_end(fmsg);
>>>>>>> + if (err)
>>>>>>> + goto unlock;
>>>>>>> + }
>>>>>>> + err = devlink_fmsg_arr_pair_nest_end(fmsg);
>>>>>>> + if (err)
>>>>>>> + goto unlock;
>>>>>>> +
>>>>>>> +unlock:
>>>>>>> + mutex_unlock(&priv->state_lock);
>>>>>>> + return err;
>>>>>>> +}
>>>>>>> +
>>>>>>> +static int mlx5e_tx_reporter_sw_dump(struct devlink_health_reporter *reporter,
>>>>>>> + struct devlink_fmsg *fmsg, void *context)
>>>>>>> +{
>>>>>>> + struct mlx5e_priv *priv = devlink_health_reporter_priv(reporter);
>>>>>>> + struct mlx5e_tx_err_ctx *err_ctx = context;
>>>>>>> +
>>>>>>> + return err_ctx ? mlx5e_tx_reporter_sw_dump_from_ctx(priv, err_ctx->sq,
>>>>>>> + fmsg) :
>>>>>>> + mlx5e_tx_reporter_sw_dump_all(priv, fmsg);
>>>>>>> +}
>>>>>>> +
>>>>>>> static const struct devlink_health_reporter_ops mlx5_tx_reporter_ops = {
>>>>>>> .name = "tx",
>>>>>>> .recover = mlx5e_tx_reporter_recover,
>>>>>>> .diagnose = mlx5e_tx_reporter_diagnose,
>>>>>>> + .dump = mlx5e_tx_reporter_sw_dump,
>>>>>>> };
>>>>>>>
>>>>>>> #define MLX5_REPORTER_TX_GRACEFUL_PERIOD 500
>>>>>>> --
>>>>>>> 2.14.1
>>>>>>>
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