From 27600805e62f800bacf990354632eae4e487d34c Mon Sep 17 00:00:00 2001 From: Yazen Ghannam Date: Thu, 3 Sep 2026 10:43:25 -0500 Subject: x86/amd_node: Fix PCI device reference counting in amd_smn_init() The local "root" pointer is a temporary variable used during the device search. Therefore, refcount related to the search iterators should be cleaned up after the search is complete. Use the __free() cleanup macro to ensure the refcount is decremented when the temporary pointer goes out of scope. Additionally, increment the refcount when caching a root pointer. This ensures the in-use refcount is separate from the temporary search refcounting. Finally, drop the redundant "root = NULL" before the second search loop. The pci_get_class() iterator always decrements the refcount of its "from" argument, so the first loop can only fall through with "root" already NULL. Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching") Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com Reported-by: Sashiko Assisted-by: LLM Signed-off-by: Yazen Ghannam Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Mario Limonciello (AMD) Cc: Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com --- fs/netfs/direct_read.c | 255 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 255 insertions(+) create mode 100644 fs/netfs/direct_read.c (limited to 'fs/netfs/direct_read.c') diff --git a/fs/netfs/direct_read.c b/fs/netfs/direct_read.c new file mode 100644 index 000000000..6a8fb0d55 --- /dev/null +++ b/fs/netfs/direct_read.c @@ -0,0 +1,255 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Direct I/O support. + * + * Copyright (C) 2023 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "internal.h" + +static void netfs_prepare_dio_read_iterator(struct netfs_io_subrequest *subreq) +{ + struct netfs_io_request *rreq = subreq->rreq; + size_t rsize; + + rsize = umin(subreq->len, rreq->io_streams[0].sreq_max_len); + subreq->len = rsize; + + if (unlikely(rreq->io_streams[0].sreq_max_segs)) { + size_t limit = netfs_limit_iter(&rreq->buffer.iter, 0, rsize, + rreq->io_streams[0].sreq_max_segs); + + if (limit < rsize) { + subreq->len = limit; + trace_netfs_sreq(subreq, netfs_sreq_trace_limited); + } + } + + trace_netfs_sreq(subreq, netfs_sreq_trace_prepare); + + subreq->io_iter = rreq->buffer.iter; + iov_iter_truncate(&subreq->io_iter, subreq->len); + iov_iter_advance(&rreq->buffer.iter, subreq->len); +} + +/* + * Perform a read to a buffer from the server, slicing up the region to be read + * according to the network rsize. + */ +static void netfs_dispatch_unbuffered_reads(struct netfs_io_request *rreq) +{ + unsigned long long start = rreq->start; + ssize_t size = rreq->len; + int ret; + + do { + struct netfs_io_subrequest *subreq; + ssize_t slice; + + subreq = netfs_alloc_subrequest(rreq); + if (!subreq) { + /* Stash the error in the request if there's not + * already an error set. + */ + cmpxchg(&rreq->error, 0, -ENOMEM); + break; + } + + subreq->source = NETFS_DOWNLOAD_FROM_SERVER; + subreq->start = start; + subreq->len = size; + + netfs_queue_read(rreq, subreq); + + netfs_stat(&netfs_n_rh_download); + if (rreq->netfs_ops->prepare_read) { + ret = rreq->netfs_ops->prepare_read(subreq); + if (ret < 0) { + netfs_cancel_read(subreq, ret); + break; + } + } + + netfs_prepare_dio_read_iterator(subreq); + slice = subreq->len; + size -= slice; + start += slice; + rreq->submitted += slice; + if (size <= 0) { + smp_wmb(); /* Write lists before ALL_QUEUED. */ + set_bit(NETFS_RREQ_ALL_QUEUED, &rreq->flags); + } + + rreq->netfs_ops->issue_read(subreq); + + if (test_bit(NETFS_RREQ_PAUSE, &rreq->flags)) + netfs_wait_for_paused_read(rreq); + if (test_bit(NETFS_RREQ_FAILED, &rreq->flags)) + break; + cond_resched(); + } while (size > 0); + + if (unlikely(size > 0)) { + smp_wmb(); /* Write lists before ALL_QUEUED. */ + set_bit(NETFS_RREQ_ALL_QUEUED, &rreq->flags); + netfs_wake_collector(rreq); + } +} + +/* + * Perform a read to an application buffer, bypassing the pagecache and the + * local disk cache. + */ +static ssize_t netfs_unbuffered_read(struct netfs_io_request *rreq, bool sync) +{ + ssize_t ret; + + _enter("R=%x %llx-%llx", + rreq->debug_id, rreq->start, rreq->start + rreq->len - 1); + + if (rreq->len == 0) { + pr_err("Zero-sized read [R=%x]\n", rreq->debug_id); + netfs_put_request(rreq, netfs_rreq_trace_put_discard); + return -EIO; + } + + // TODO: Use bounce buffer if requested + + inode_dio_begin(rreq->inode); + netfs_dispatch_unbuffered_reads(rreq); + + /* The collector will get run, even if we don't manage to submit any + * subreqs, so we shouldn't call inode_dio_end() here. + */ + + if (sync) + ret = netfs_wait_for_read(rreq); + else + ret = -EIOCBQUEUED; + + _leave(" = %zd", ret); + return ret; +} + +/** + * netfs_unbuffered_read_iter_locked - Perform an unbuffered or direct I/O read + * @iocb: The I/O control descriptor describing the read + * @iter: The output buffer (also specifies read length) + * + * Perform an unbuffered I/O or direct I/O from the file in @iocb to the + * output buffer. No use is made of the pagecache. + * + * The caller must hold any appropriate locks. + */ +ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *iter) +{ + struct netfs_io_request *rreq; + ssize_t ret; + size_t orig_count = iov_iter_count(iter); + bool sync = is_sync_kiocb(iocb); + + _enter(""); + + if (!orig_count) + return 0; /* Don't update atime */ + + ret = kiocb_write_and_wait(iocb, orig_count); + if (ret < 0) + return ret; + file_accessed(iocb->ki_filp); + + rreq = netfs_alloc_request(iocb->ki_filp->f_mapping, iocb->ki_filp, + iocb->ki_pos, orig_count, + iocb->ki_flags & IOCB_DIRECT ? + NETFS_DIO_READ : NETFS_UNBUFFERED_READ); + if (IS_ERR(rreq)) + return PTR_ERR(rreq); + + netfs_stat(&netfs_n_rh_dio_read); + trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_dio_read); + + /* If this is an async op, we have to keep track of the destination + * buffer for ourselves as the caller's iterator will be trashed when + * we return. + * + * In such a case, extract an iterator to represent as much of the the + * output buffer as we can manage. Note that the extraction might not + * be able to allocate a sufficiently large bvec array and may shorten + * the request. + */ + if (user_backed_iter(iter)) { + ret = netfs_extract_user_iter(iter, rreq->len, &rreq->buffer.iter, 0); + if (ret < 0) + goto error_put; + rreq->direct_bv = (struct bio_vec *)rreq->buffer.iter.bvec; + rreq->direct_bv_count = ret; + rreq->direct_bv_unpin = iov_iter_extract_will_pin(iter); + rreq->len = iov_iter_count(&rreq->buffer.iter); + } else { + rreq->buffer.iter = *iter; + rreq->len = orig_count; + rreq->direct_bv_unpin = false; + iov_iter_advance(iter, orig_count); + } + + // TODO: Set up bounce buffer if needed + + if (!sync) { + rreq->iocb = iocb; + __set_bit(NETFS_RREQ_OFFLOAD_COLLECTION, &rreq->flags); + } + + ret = netfs_unbuffered_read(rreq, sync); + if (ret < 0) + goto out; /* May be -EIOCBQUEUED */ + if (sync) { + // TODO: Copy from bounce buffer + iocb->ki_pos += rreq->transferred; + ret = rreq->transferred; + } + +out: + netfs_put_request(rreq, netfs_rreq_trace_put_return); + if (ret > 0) + orig_count -= ret; + return ret; + +error_put: + netfs_put_failed_request(rreq); + return ret; +} +EXPORT_SYMBOL(netfs_unbuffered_read_iter_locked); + +/** + * netfs_unbuffered_read_iter - Perform an unbuffered or direct I/O read + * @iocb: The I/O control descriptor describing the read + * @iter: The output buffer (also specifies read length) + * + * Perform an unbuffered I/O or direct I/O from the file in @iocb to the + * output buffer. No use is made of the pagecache. + */ +ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter) +{ + struct inode *inode = file_inode(iocb->ki_filp); + ssize_t ret; + + if (!iter->count) + return 0; /* Don't update atime */ + + ret = netfs_start_io_direct(inode); + if (ret == 0) { + ret = netfs_unbuffered_read_iter_locked(iocb, iter); + netfs_end_io_direct(inode); + } + return ret; +} +EXPORT_SYMBOL(netfs_unbuffered_read_iter); -- cgit v1.3.1