From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- sound/firewire/packets-buffer.c | 77 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 77 insertions(+) create mode 100644 sound/firewire/packets-buffer.c (limited to 'sound/firewire/packets-buffer.c') diff --git a/sound/firewire/packets-buffer.c b/sound/firewire/packets-buffer.c new file mode 100644 index 000000000..2093a5fbd --- /dev/null +++ b/sound/firewire/packets-buffer.c @@ -0,0 +1,77 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * helpers for managing a buffer for many packets + * + * Copyright (c) Clemens Ladisch + */ + +#include +#include +#include +#include "packets-buffer.h" + +/** + * iso_packets_buffer_init - allocates the memory for packets + * @b: the buffer structure to initialize + * @unit: the device at the other end of the stream + * @count: the number of packets + * @packet_size: the (maximum) size of a packet, in bytes + * @direction: %DMA_TO_DEVICE or %DMA_FROM_DEVICE + */ +int iso_packets_buffer_init(struct iso_packets_buffer *b, struct fw_unit *unit, + unsigned int count, unsigned int packet_size, + enum dma_data_direction direction) +{ + unsigned int packets_per_page, pages; + unsigned int i, page_index, offset_in_page; + void *p; + int err; + + b->packets = kmalloc_objs(*b->packets, count); + if (!b->packets) { + err = -ENOMEM; + goto error; + } + + packet_size = L1_CACHE_ALIGN(packet_size); + packets_per_page = PAGE_SIZE / packet_size; + if (WARN_ON(!packets_per_page)) { + err = -EINVAL; + goto err_packets; + } + pages = DIV_ROUND_UP(count, packets_per_page); + + err = fw_iso_buffer_init(&b->iso_buffer, fw_parent_device(unit)->card, + pages, direction); + if (err < 0) + goto err_packets; + + for (i = 0; i < count; ++i) { + page_index = i / packets_per_page; + p = page_address(b->iso_buffer.pages[page_index]); + offset_in_page = (i % packets_per_page) * packet_size; + b->packets[i].buffer = p + offset_in_page; + b->packets[i].offset = page_index * PAGE_SIZE + offset_in_page; + } + + return 0; + +err_packets: + kfree(b->packets); +error: + return err; +} +EXPORT_SYMBOL(iso_packets_buffer_init); + +/** + * iso_packets_buffer_destroy - frees packet buffer resources + * @b: the buffer structure to free + * @unit: the device at the other end of the stream + */ +void iso_packets_buffer_destroy(struct iso_packets_buffer *b, + struct fw_unit *unit) +{ + fw_iso_buffer_destroy(&b->iso_buffer, fw_parent_device(unit)->card); + kfree(b->packets); +} +EXPORT_SYMBOL(iso_packets_buffer_destroy); -- cgit v1.3.1