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 --- tools/perf/util/cap.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 tools/perf/util/cap.c (limited to 'tools/perf/util/cap.c') diff --git a/tools/perf/util/cap.c b/tools/perf/util/cap.c new file mode 100644 index 000000000..272bd8255 --- /dev/null +++ b/tools/perf/util/cap.c @@ -0,0 +1,46 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Capability utilities + */ + +#include "cap.h" +#include "debug.h" +#include +#include +#include +#include + +#define MAX_LINUX_CAPABILITY_U32S _LINUX_CAPABILITY_U32S_3 + +bool perf_cap__capable(int cap) +{ + struct __user_cap_header_struct header = { + .version = _LINUX_CAPABILITY_VERSION_3, + .pid = 0, + }; + struct __user_cap_data_struct data[MAX_LINUX_CAPABILITY_U32S] = {}; + __u32 cap_val; + + while (syscall(SYS_capget, &header, &data[0]) == -1) { + /* Retry, first attempt has set the header.version correctly. */ + if (errno == EINVAL && header.version != _LINUX_CAPABILITY_VERSION_3 && + header.version == _LINUX_CAPABILITY_VERSION_1) + continue; + + pr_debug2("capget syscall failed (%m) fall back on root check\n"); + return geteuid() == 0; + } + + /* Extract the relevant capability bit. */ + if (cap >= 32) { + if (header.version == _LINUX_CAPABILITY_VERSION_3) { + cap_val = data[1].effective; + } else { + /* Capability beyond 32 is requested but only 32 are supported. */ + return false; + } + } else { + cap_val = data[0].effective; + } + return (cap_val & (1 << (cap & 0x1f))) != 0; +} -- cgit v1.3.1