From: Caleb Sander csander@purestorage.com
[ Upstream commit 5401c3e0992860b11fb4b25796e4c4f1921740df ]
By default, qed_mcp_cmd_and_union() delays 10us at a time in a loop that can run 500K times, so calls to qed_mcp_nvm_rd_cmd() may block the current thread for over 5s. We observed thread scheduling delays over 700ms in production, with stacktraces pointing to this code as the culprit.
qed_mcp_trace_dump() is called from ethtool, so sleeping is permitted. It already can sleep in qed_mcp_halt(), which calls qed_mcp_cmd(). Add a "can sleep" parameter to qed_find_nvram_image() and qed_nvram_read() so they can sleep during qed_mcp_trace_dump(). qed_mcp_trace_get_meta_info() and qed_mcp_trace_read_meta(), called only by qed_mcp_trace_dump(), allow these functions to sleep. I can't tell if the other caller (qed_grc_dump_mcp_hw_dump()) can sleep, so keep b_can_sleep set to false when it calls these functions.
An example stacktrace from a custom warning we added to the kernel showing a thread that has not scheduled despite long needing resched: [ 2745.362925,17] ------------[ cut here ]------------ [ 2745.362941,17] WARNING: CPU: 23 PID: 5640 at arch/x86/kernel/irq.c:233 do_IRQ+0x15e/0x1a0() [ 2745.362946,17] Thread not rescheduled for 744 ms after irq 99 [ 2745.362956,17] Modules linked in: ... [ 2745.363339,17] CPU: 23 PID: 5640 Comm: lldpd Tainted: P O 4.4.182+ #202104120910+6d1da174272d.61x [ 2745.363343,17] Hardware name: FOXCONN MercuryB/Quicksilver Controller, BIOS H11P1N09 07/08/2020 [ 2745.363346,17] 0000000000000000 ffff885ec07c3ed8 ffffffff8131eb2f ffff885ec07c3f20 [ 2745.363358,17] ffffffff81d14f64 ffff885ec07c3f10 ffffffff81072ac2 ffff88be98ed0000 [ 2745.363369,17] 0000000000000063 0000000000000174 0000000000000074 0000000000000000 [ 2745.363379,17] Call Trace: [ 2745.363382,17] <IRQ> [<ffffffff8131eb2f>] dump_stack+0x8e/0xcf [ 2745.363393,17] [<ffffffff81072ac2>] warn_slowpath_common+0x82/0xc0 [ 2745.363398,17] [<ffffffff81072b4c>] warn_slowpath_fmt+0x4c/0x50 [ 2745.363404,17] [<ffffffff810d5a8e>] ? rcu_irq_exit+0xae/0xc0 [ 2745.363408,17] [<ffffffff817c99fe>] do_IRQ+0x15e/0x1a0 [ 2745.363413,17] [<ffffffff817c7ac9>] common_interrupt+0x89/0x89 [ 2745.363416,17] <EOI> [<ffffffff8132aa74>] ? delay_tsc+0x24/0x50 [ 2745.363425,17] [<ffffffff8132aa04>] __udelay+0x34/0x40 [ 2745.363457,17] [<ffffffffa04d45ff>] qed_mcp_cmd_and_union+0x36f/0x7d0 [qed] [ 2745.363473,17] [<ffffffffa04d5ced>] qed_mcp_nvm_rd_cmd+0x4d/0x90 [qed] [ 2745.363490,17] [<ffffffffa04e1dc7>] qed_mcp_trace_dump+0x4a7/0x630 [qed] [ 2745.363504,17] [<ffffffffa04e2556>] ? qed_fw_asserts_dump+0x1d6/0x1f0 [qed] [ 2745.363520,17] [<ffffffffa04e4ea7>] qed_dbg_mcp_trace_get_dump_buf_size+0x37/0x80 [qed] [ 2745.363536,17] [<ffffffffa04ea881>] qed_dbg_feature_size+0x61/0xa0 [qed] [ 2745.363551,17] [<ffffffffa04eb427>] qed_dbg_all_data_size+0x247/0x260 [qed] [ 2745.363560,17] [<ffffffffa0482c10>] qede_get_regs_len+0x30/0x40 [qede] [ 2745.363566,17] [<ffffffff816c9783>] ethtool_get_drvinfo+0xe3/0x190 [ 2745.363570,17] [<ffffffff816cc152>] dev_ethtool+0x1362/0x2140 [ 2745.363575,17] [<ffffffff8109bcc6>] ? finish_task_switch+0x76/0x260 [ 2745.363580,17] [<ffffffff817c2116>] ? __schedule+0x3c6/0x9d0 [ 2745.363585,17] [<ffffffff810dbd50>] ? hrtimer_start_range_ns+0x1d0/0x370 [ 2745.363589,17] [<ffffffff816c1e5b>] ? dev_get_by_name_rcu+0x6b/0x90 [ 2745.363594,17] [<ffffffff816de6a8>] dev_ioctl+0xe8/0x710 [ 2745.363599,17] [<ffffffff816a58a8>] sock_do_ioctl+0x48/0x60 [ 2745.363603,17] [<ffffffff816a5d87>] sock_ioctl+0x1c7/0x280 [ 2745.363608,17] [<ffffffff8111f393>] ? seccomp_phase1+0x83/0x220 [ 2745.363612,17] [<ffffffff811e3503>] do_vfs_ioctl+0x2b3/0x4e0 [ 2745.363616,17] [<ffffffff811e3771>] SyS_ioctl+0x41/0x70 [ 2745.363619,17] [<ffffffff817c6ffe>] entry_SYSCALL_64_fastpath+0x1e/0x79 [ 2745.363622,17] ---[ end trace f6954aa440266421 ]---
Fixes: c965db4446291 ("qed: Add support for debug data collection") Signed-off-by: Caleb Sander csander@purestorage.com Acked-by: Alok Prasad palok@marvell.com Link: https://lore.kernel.org/r/20230103233021.1457646-1-csander@purestorage.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/qlogic/qed/qed_debug.c | 28 +++++++++++++++------ 1 file changed, 20 insertions(+), 8 deletions(-)
diff --git a/drivers/net/ethernet/qlogic/qed/qed_debug.c b/drivers/net/ethernet/qlogic/qed/qed_debug.c index 86ecb080b153..cdcead614e9f 100644 --- a/drivers/net/ethernet/qlogic/qed/qed_debug.c +++ b/drivers/net/ethernet/qlogic/qed/qed_debug.c @@ -1832,7 +1832,8 @@ static enum dbg_status qed_find_nvram_image(struct qed_hwfn *p_hwfn, struct qed_ptt *p_ptt, u32 image_type, u32 *nvram_offset_bytes, - u32 *nvram_size_bytes) + u32 *nvram_size_bytes, + bool b_can_sleep) { u32 ret_mcp_resp, ret_mcp_param, ret_txn_size; struct mcp_file_att file_att; @@ -1846,7 +1847,8 @@ static enum dbg_status qed_find_nvram_image(struct qed_hwfn *p_hwfn, &ret_mcp_resp, &ret_mcp_param, &ret_txn_size, - (u32 *)&file_att, false); + (u32 *)&file_att, + b_can_sleep);
/* Check response */ if (nvm_result || (ret_mcp_resp & FW_MSG_CODE_MASK) != @@ -1873,7 +1875,9 @@ static enum dbg_status qed_find_nvram_image(struct qed_hwfn *p_hwfn, static enum dbg_status qed_nvram_read(struct qed_hwfn *p_hwfn, struct qed_ptt *p_ptt, u32 nvram_offset_bytes, - u32 nvram_size_bytes, u32 *ret_buf) + u32 nvram_size_bytes, + u32 *ret_buf, + bool b_can_sleep) { u32 ret_mcp_resp, ret_mcp_param, ret_read_size, bytes_to_copy; s32 bytes_left = nvram_size_bytes; @@ -1899,7 +1903,7 @@ static enum dbg_status qed_nvram_read(struct qed_hwfn *p_hwfn, &ret_mcp_resp, &ret_mcp_param, &ret_read_size, (u32 *)((u8 *)ret_buf + read_offset), - false)) + b_can_sleep)) return DBG_STATUS_NVRAM_READ_FAILED;
/* Check response */ @@ -3380,7 +3384,8 @@ static u32 qed_grc_dump_mcp_hw_dump(struct qed_hwfn *p_hwfn, p_ptt, NVM_TYPE_HW_DUMP_OUT, &hw_dump_offset_bytes, - &hw_dump_size_bytes); + &hw_dump_size_bytes, + false); if (status != DBG_STATUS_OK) return 0;
@@ -3397,7 +3402,9 @@ static u32 qed_grc_dump_mcp_hw_dump(struct qed_hwfn *p_hwfn, status = qed_nvram_read(p_hwfn, p_ptt, hw_dump_offset_bytes, - hw_dump_size_bytes, dump_buf + offset); + hw_dump_size_bytes, + dump_buf + offset, + false); if (status != DBG_STATUS_OK) { DP_NOTICE(p_hwfn, "Failed to read MCP HW Dump image from NVRAM\n"); @@ -4123,7 +4130,9 @@ static enum dbg_status qed_mcp_trace_get_meta_info(struct qed_hwfn *p_hwfn, return qed_find_nvram_image(p_hwfn, p_ptt, nvram_image_type, - trace_meta_offset, trace_meta_size); + trace_meta_offset, + trace_meta_size, + true); }
/* Reads the MCP Trace meta data from NVRAM into the specified buffer */ @@ -4139,7 +4148,10 @@ static enum dbg_status qed_mcp_trace_read_meta(struct qed_hwfn *p_hwfn, /* Read meta data from NVRAM */ status = qed_nvram_read(p_hwfn, p_ptt, - nvram_offset_in_bytes, size_in_bytes, buf); + nvram_offset_in_bytes, + size_in_bytes, + buf, + true); if (status != DBG_STATUS_OK) return status;