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From 430c2546a4d8503d963bab99abf0083e98019052 Mon Sep 17 00:00:00 2001 |
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From: Shaul Triebitz <shaul.triebitz@intel.com> |
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Date: Wed, 6 Jun 2018 17:20:58 +0300 |
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Subject: [PATCH 027/145] iwlwifi: pcie: avoid empty free RB queue |
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[ Upstream commit 868a1e863f95183f00809363fefba6d4f5bcd116 ] |
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If all free RB queues are empty, the driver will never restock the |
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free RB queue. That's because the restocking happens in the Rx flow, |
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and if the free queue is empty there will be no Rx. |
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Although there's a background worker (a.k.a. allocator) allocating |
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memory for RBs so that the Rx handler can restock them, the worker may |
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run only after the free queue has become empty (and then it is too |
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late for restocking as explained above). |
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There is a solution for that called 'emergency': If the number of used |
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RB's reaches half the amount of all RB's, the Rx handler will not wait |
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for the allocator but immediately allocate memory for the used RB's |
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and restock the free queue. |
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But, since the used RB's is per queue, it may happen that the used |
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RB's are spread between the queues such that the emergency check will |
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fail for each of the queues |
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(and still run out of RBs, causing the above symptom). |
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To fix it, move to emergency mode if the sum of *all* used RBs (for |
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all Rx queues) reaches half the amount of all RB's |
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Signed-off-by: Shaul Triebitz <shaul.triebitz@intel.com> |
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Signed-off-by: Luca Coelho <luciano.coelho@intel.com> |
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Signed-off-by: Sasha Levin <sashal@kernel.org> |
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--- |
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drivers/net/wireless/intel/iwlwifi/pcie/rx.c | 32 +++++++++++++------- |
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1 file changed, 21 insertions(+), 11 deletions(-) |
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diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/rx.c b/drivers/net/wireless/intel/iwlwifi/pcie/rx.c |
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index d017aa2a0a8b..d4a31e014c82 100644 |
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--- a/drivers/net/wireless/intel/iwlwifi/pcie/rx.c |
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+++ b/drivers/net/wireless/intel/iwlwifi/pcie/rx.c |
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@@ -1144,6 +1144,14 @@ void iwl_pcie_rx_free(struct iwl_trans *trans) |
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kfree(trans_pcie->rxq); |
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} |
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+static void iwl_pcie_rx_move_to_allocator(struct iwl_rxq *rxq, |
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+ struct iwl_rb_allocator *rba) |
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+{ |
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+ spin_lock(&rba->lock); |
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+ list_splice_tail_init(&rxq->rx_used, &rba->rbd_empty); |
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+ spin_unlock(&rba->lock); |
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+} |
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+ |
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/* |
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* iwl_pcie_rx_reuse_rbd - Recycle used RBDs |
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* |
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@@ -1175,9 +1183,7 @@ static void iwl_pcie_rx_reuse_rbd(struct iwl_trans *trans, |
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if ((rxq->used_count % RX_CLAIM_REQ_ALLOC) == RX_POST_REQ_ALLOC) { |
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/* Move the 2 RBDs to the allocator ownership. |
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Allocator has another 6 from pool for the request completion*/ |
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- spin_lock(&rba->lock); |
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- list_splice_tail_init(&rxq->rx_used, &rba->rbd_empty); |
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- spin_unlock(&rba->lock); |
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+ iwl_pcie_rx_move_to_allocator(rxq, rba); |
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atomic_inc(&rba->req_pending); |
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queue_work(rba->alloc_wq, &rba->rx_alloc); |
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@@ -1396,10 +1402,18 @@ static void iwl_pcie_rx_handle(struct iwl_trans *trans, int queue) |
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IWL_DEBUG_RX(trans, "Q %d: HW = SW = %d\n", rxq->id, r); |
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while (i != r) { |
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+ struct iwl_rb_allocator *rba = &trans_pcie->rba; |
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struct iwl_rx_mem_buffer *rxb; |
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- |
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- if (unlikely(rxq->used_count == rxq->queue_size / 2)) |
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+ /* number of RBDs still waiting for page allocation */ |
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+ u32 rb_pending_alloc = |
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+ atomic_read(&trans_pcie->rba.req_pending) * |
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+ RX_CLAIM_REQ_ALLOC; |
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+ |
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+ if (unlikely(rb_pending_alloc >= rxq->queue_size / 2 && |
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+ !emergency)) { |
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+ iwl_pcie_rx_move_to_allocator(rxq, rba); |
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emergency = true; |
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+ } |
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rxb = iwl_pcie_get_rxb(trans, rxq, i); |
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if (!rxb) |
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@@ -1421,17 +1435,13 @@ static void iwl_pcie_rx_handle(struct iwl_trans *trans, int queue) |
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iwl_pcie_rx_allocator_get(trans, rxq); |
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if (rxq->used_count % RX_CLAIM_REQ_ALLOC == 0 && !emergency) { |
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- struct iwl_rb_allocator *rba = &trans_pcie->rba; |
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- |
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/* Add the remaining empty RBDs for allocator use */ |
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- spin_lock(&rba->lock); |
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- list_splice_tail_init(&rxq->rx_used, &rba->rbd_empty); |
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- spin_unlock(&rba->lock); |
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+ iwl_pcie_rx_move_to_allocator(rxq, rba); |
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} else if (emergency) { |
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count++; |
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if (count == 8) { |
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count = 0; |
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- if (rxq->used_count < rxq->queue_size / 3) |
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+ if (rb_pending_alloc < rxq->queue_size / 3) |
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emergency = false; |
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rxq->read = i; |
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-- |
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2.19.1 |
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