From 913eda2b08cc49d31f382579e2be34c2709eb789 Mon Sep 17 00:00:00 2001 From: Maciej Fijalkowski Date: Wed, 18 Oct 2023 18:39:08 +0200 Subject: [PATCH] i40e: xsk: remove count_mask Cited commit introduced a neat way of updating next_to_clean that does not require boundary checks on each increment. This was done by masking the new value with (ring length - 1) mask. Problem is that this is applicable only for power of 2 ring sizes, for every other size this assumption can not be made. In turn, it leads to cleaning descriptors out of order as well as splats: [ 1388.411915] Workqueue: events xp_release_deferred [ 1388.411919] RIP: 0010:xp_free+0x1a/0x50 [ 1388.411921] Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 55 48 8b 57 70 48 8d 47 70 48 89 e5 48 39 d0 74 06 <5d> c3 cc cc cc cc 48 8b 57 60 83 82 b8 00 00 00 01 48 8b 57 60 48 [ 1388.411922] RSP: 0018:ffa0000000a83cb0 EFLAGS: 00000206 [ 1388.411923] RAX: ff11000119aa5030 RBX: 000000000000001d RCX: ff110001129b6e50 [ 1388.411924] RDX: ff11000119aa4fa0 RSI: 0000000055555554 RDI: ff11000119aa4fc0 [ 1388.411925] RBP: ffa0000000a83cb0 R08: 0000000000000000 R09: 0000000000000000 [ 1388.411926] R10: 0000000000000001 R11: 0000000000000000 R12: ff11000115829b80 [ 1388.411927] R13: 000000000000005f R14: 0000000000000000 R15: ff11000119aa4fc0 [ 1388.411928] FS: 0000000000000000(0000) GS:ff11000277e00000(0000) knlGS:0000000000000000 [ 1388.411929] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1388.411930] CR2: 00007f1f564e6c14 CR3: 000000000783c005 CR4: 0000000000771ef0 [ 1388.411931] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 1388.411931] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 1388.411932] PKRU: 55555554 [ 1388.411933] Call Trace: [ 1388.411934] [ 1388.411935] ? show_regs+0x6e/0x80 [ 1388.411937] ? watchdog_timer_fn+0x1d2/0x240 [ 1388.411939] ? __pfx_watchdog_timer_fn+0x10/0x10 [ 1388.411941] ? __hrtimer_run_queues+0x10e/0x290 [ 1388.411945] ? clockevents_program_event+0xae/0x130 [ 1388.411947] ? hrtimer_interrupt+0x105/0x240 [ 1388.411949] ? __sysvec_apic_timer_interrupt+0x54/0x150 [ 1388.411952] ? sysvec_apic_timer_interrupt+0x7f/0x90 [ 1388.411955] [ 1388.411955] [ 1388.411956] ? asm_sysvec_apic_timer_interrupt+0x1f/0x30 [ 1388.411958] ? xp_free+0x1a/0x50 [ 1388.411960] i40e_xsk_clean_rx_ring+0x5d/0x100 [i40e] [ 1388.411968] i40e_clean_rx_ring+0x14c/0x170 [i40e] [ 1388.411977] i40e_queue_pair_disable+0xda/0x260 [i40e] [ 1388.411986] i40e_xsk_pool_setup+0x192/0x1d0 [i40e] [ 1388.411993] i40e_reconfig_rss_queues+0x1f0/0x1450 [i40e] [ 1388.412002] xp_disable_drv_zc+0x73/0xf0 [ 1388.412004] ? mutex_lock+0x17/0x50 [ 1388.412007] xp_release_deferred+0x2b/0xc0 [ 1388.412010] process_one_work+0x178/0x350 [ 1388.412011] ? __pfx_worker_thread+0x10/0x10 [ 1388.412012] worker_thread+0x2f7/0x420 [ 1388.412014] ? __pfx_worker_thread+0x10/0x10 [ 1388.412015] kthread+0xf8/0x130 [ 1388.412017] ? __pfx_kthread+0x10/0x10 [ 1388.412019] ret_from_fork+0x3d/0x60 [ 1388.412021] ? __pfx_kthread+0x10/0x10 [ 1388.412023] ret_from_fork_asm+0x1b/0x30 [ 1388.412026] It comes from picking wrong ring entries when cleaning xsk buffers during pool detach. Remove the count_mask logic and use they boundary check when updating next_to_process (which used to be a next_to_clean). Fixes: c8a8ca3408dc ("i40e: remove unnecessary memory writes of the next to clean pointer") Reported-by: Tushar Vyavahare Tested-by: Tushar Vyavahare Signed-off-by: Maciej Fijalkowski Reviewed-by: Jacob Keller Link: https://lore.kernel.org/r/20231018163908.40841-1-maciej.fijalkowski@intel.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/intel/i40e/i40e_xsk.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c index 37f41c8..7d991e4 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c +++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c @@ -437,12 +437,12 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) unsigned int total_rx_bytes = 0, total_rx_packets = 0; u16 next_to_process = rx_ring->next_to_process; u16 next_to_clean = rx_ring->next_to_clean; - u16 count_mask = rx_ring->count - 1; unsigned int xdp_res, xdp_xmit = 0; struct xdp_buff *first = NULL; + u32 count = rx_ring->count; struct bpf_prog *xdp_prog; + u32 entries_to_alloc; bool failure = false; - u16 cleaned_count; if (next_to_process != next_to_clean) first = *i40e_rx_bi(rx_ring, next_to_clean); @@ -475,7 +475,8 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) qword); bi = *i40e_rx_bi(rx_ring, next_to_process); xsk_buff_free(bi); - next_to_process = (next_to_process + 1) & count_mask; + if (++next_to_process == count) + next_to_process = 0; continue; } @@ -493,7 +494,8 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) else if (i40e_add_xsk_frag(rx_ring, first, bi, size)) break; - next_to_process = (next_to_process + 1) & count_mask; + if (++next_to_process == count) + next_to_process = 0; if (i40e_is_non_eop(rx_ring, rx_desc)) continue; @@ -513,10 +515,10 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) rx_ring->next_to_clean = next_to_clean; rx_ring->next_to_process = next_to_process; - cleaned_count = (next_to_clean - rx_ring->next_to_use - 1) & count_mask; - if (cleaned_count >= I40E_RX_BUFFER_WRITE) - failure |= !i40e_alloc_rx_buffers_zc(rx_ring, cleaned_count); + entries_to_alloc = I40E_DESC_UNUSED(rx_ring); + if (entries_to_alloc >= I40E_RX_BUFFER_WRITE) + failure |= !i40e_alloc_rx_buffers_zc(rx_ring, entries_to_alloc); i40e_finalize_xdp_rx(rx_ring, xdp_xmit); i40e_update_rx_stats(rx_ring, total_rx_bytes, total_rx_packets); @@ -752,14 +754,16 @@ int i40e_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags) void i40e_xsk_clean_rx_ring(struct i40e_ring *rx_ring) { - u16 count_mask = rx_ring->count - 1; u16 ntc = rx_ring->next_to_clean; u16 ntu = rx_ring->next_to_use; - for ( ; ntc != ntu; ntc = (ntc + 1) & count_mask) { + while (ntc != ntu) { struct xdp_buff *rx_bi = *i40e_rx_bi(rx_ring, ntc); xsk_buff_free(rx_bi); + ntc++; + if (ntc >= rx_ring->count) + ntc = 0; } } -- 2.7.4