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/stack.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 76 insertions(+) create mode 100644 fs/stack.c (limited to 'fs/stack.c') diff --git a/fs/stack.c b/fs/stack.c new file mode 100644 index 000000000..d8c782e06 --- /dev/null +++ b/fs/stack.c @@ -0,0 +1,76 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include + +/* does _NOT_ require i_rwsem to be held. + * + * This function cannot be inlined since i_size_{read,write} is rather + * heavy-weight on 32-bit systems + */ +void fsstack_copy_inode_size(struct inode *dst, struct inode *src) +{ + loff_t i_size; + blkcnt_t i_blocks; + + /* + * i_size_read() includes its own seqlocking and protection from + * preemption (see include/linux/fs.h): we need nothing extra for + * that here, and prefer to avoid nesting locks than attempt to keep + * i_size and i_blocks in sync together. + */ + i_size = i_size_read(src); + + /* + * But on 32-bit, we ought to make an effort to keep the two halves of + * i_blocks in sync despite SMP or PREEMPTION - though stat's + * generic_fillattr() doesn't bother, and we won't be applying quotas + * (where i_blocks does become important) at the upper level. + * + * We don't actually know what locking is used at the lower level; + * but if it's a filesystem that supports quotas, it will be using + * i_lock as in inode_add_bytes(). + */ + if (sizeof(i_blocks) > sizeof(long)) + spin_lock(&src->i_lock); + i_blocks = src->i_blocks; + if (sizeof(i_blocks) > sizeof(long)) + spin_unlock(&src->i_lock); + + /* + * If CONFIG_SMP or CONFIG_PREEMPTION on 32-bit, it's vital for + * fsstack_copy_inode_size() to hold some lock around + * i_size_write(), otherwise i_size_read() may spin forever (see + * include/linux/fs.h). We don't necessarily hold i_rwsem when this + * is called, so take i_lock for that case. + * + * And if on 32-bit, continue our effort to keep the two halves of + * i_blocks in sync despite SMP or PREEMPTION: use i_lock for that case + * too, and do both at once by combining the tests. + * + * There is none of this locking overhead in the 64-bit case. + */ + if (sizeof(i_size) > sizeof(long) || sizeof(i_blocks) > sizeof(long)) + spin_lock(&dst->i_lock); + i_size_write(dst, i_size); + dst->i_blocks = i_blocks; + if (sizeof(i_size) > sizeof(long) || sizeof(i_blocks) > sizeof(long)) + spin_unlock(&dst->i_lock); +} +EXPORT_SYMBOL_GPL(fsstack_copy_inode_size); + +/* copy all attributes */ +void fsstack_copy_attr_all(struct inode *dest, const struct inode *src) +{ + dest->i_mode = src->i_mode; + dest->i_uid = src->i_uid; + dest->i_gid = src->i_gid; + dest->i_rdev = src->i_rdev; + inode_set_atime_to_ts(dest, inode_get_atime(src)); + inode_set_mtime_to_ts(dest, inode_get_mtime(src)); + inode_set_ctime_to_ts(dest, inode_get_ctime(src)); + dest->i_blkbits = src->i_blkbits; + dest->i_flags = src->i_flags; + set_nlink(dest, src->i_nlink); +} +EXPORT_SYMBOL_GPL(fsstack_copy_attr_all); -- cgit v1.3.1