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 --- samples/bpf/tracex4.bpf.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 samples/bpf/tracex4.bpf.c (limited to 'samples/bpf/tracex4.bpf.c') diff --git a/samples/bpf/tracex4.bpf.c b/samples/bpf/tracex4.bpf.c new file mode 100644 index 000000000..d786492fd --- /dev/null +++ b/samples/bpf/tracex4.bpf.c @@ -0,0 +1,54 @@ +/* Copyright (c) 2015 PLUMgrid, http://plumgrid.com + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + */ +#include "vmlinux.h" +#include +#include +#include + +struct pair { + u64 val; + u64 ip; +}; + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __type(key, long); + __type(value, struct pair); + __uint(max_entries, 1000000); +} my_map SEC(".maps"); + +/* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe + * example will no longer be meaningful + */ +SEC("kprobe/kmem_cache_free") +int bpf_prog1(struct pt_regs *ctx) +{ + long ptr = PT_REGS_PARM2(ctx); + + bpf_map_delete_elem(&my_map, &ptr); + return 0; +} + +SEC("kretprobe/kmem_cache_alloc_node_noprof") +int bpf_prog2(struct pt_regs *ctx) +{ + long ptr = PT_REGS_RC(ctx); + long ip = 0; + + /* get ip address of kmem_cache_alloc_node_noprof() caller */ + BPF_KRETPROBE_READ_RET_IP(ip, ctx); + + struct pair v = { + .val = bpf_ktime_get_ns(), + .ip = ip, + }; + + bpf_map_update_elem(&my_map, &ptr, &v, BPF_ANY); + return 0; +} +char _license[] SEC("license") = "GPL"; +u32 _version SEC("version") = LINUX_VERSION_CODE; -- cgit v1.3.1