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Date: Tue, 14 May 2019 14:07:51 +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
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?
>
>>
>>> 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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