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Date: Thu, 9 May 2019 10:23:34 +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
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)?
>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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