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 --- include/asm-generic/preempt.h | 114 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 114 insertions(+) create mode 100644 include/asm-generic/preempt.h (limited to 'include/asm-generic/preempt.h') diff --git a/include/asm-generic/preempt.h b/include/asm-generic/preempt.h new file mode 100644 index 000000000..c8683c046 --- /dev/null +++ b/include/asm-generic/preempt.h @@ -0,0 +1,114 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_PREEMPT_H +#define __ASM_PREEMPT_H + +#include + +#define PREEMPT_ENABLED (0) + +static __always_inline int preempt_count(void) +{ + return READ_ONCE(current_thread_info()->preempt_count); +} + +static __always_inline volatile int *preempt_count_ptr(void) +{ + return ¤t_thread_info()->preempt_count; +} + +static __always_inline void preempt_count_set(int pc) +{ + *preempt_count_ptr() = pc; +} + +/* + * must be macros to avoid header recursion hell + */ +#define init_task_preempt_count(p) do { \ + task_thread_info(p)->preempt_count = FORK_PREEMPT_COUNT; \ +} while (0) + +#define init_idle_preempt_count(p, cpu) do { \ + task_thread_info(p)->preempt_count = PREEMPT_DISABLED; \ +} while (0) + +static __always_inline void set_preempt_need_resched(void) +{ +} + +static __always_inline void clear_preempt_need_resched(void) +{ +} + +static __always_inline bool test_preempt_need_resched(void) +{ + return false; +} + +/* + * The various preempt_count add/sub methods + */ + +static __always_inline void __preempt_count_add(int val) +{ + *preempt_count_ptr() += val; +} + +static __always_inline void __preempt_count_sub(int val) +{ + *preempt_count_ptr() -= val; +} + +static __always_inline int __preempt_count_add_return(int val) +{ + *preempt_count_ptr() += val; + + return *preempt_count_ptr(); +} + +static __always_inline int __preempt_count_sub_return(int val) +{ + *preempt_count_ptr() -= val; + + return *preempt_count_ptr(); +} + +static __always_inline bool __preempt_count_dec_and_test(void) +{ + /* + * Because of load-store architectures cannot do per-cpu atomic + * operations; we cannot use PREEMPT_NEED_RESCHED because it might get + * lost. + */ + return !--*preempt_count_ptr() && tif_need_resched(); +} + +/* + * Returns true when we need to resched and can (barring IRQ state). + */ +static __always_inline bool should_resched(int preempt_offset) +{ + return unlikely(preempt_count() == preempt_offset && + tif_need_resched()); +} + +#ifdef CONFIG_PREEMPTION +extern asmlinkage void preempt_schedule(void); +extern asmlinkage void preempt_schedule_notrace(void); + +#if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY) + +void dynamic_preempt_schedule(void); +void dynamic_preempt_schedule_notrace(void); +#define __preempt_schedule() dynamic_preempt_schedule() +#define __preempt_schedule_notrace() dynamic_preempt_schedule_notrace() + +#else /* !CONFIG_PREEMPT_DYNAMIC || !CONFIG_HAVE_PREEMPT_DYNAMIC_KEY*/ + +#define __preempt_schedule() preempt_schedule() +#define __preempt_schedule_notrace() preempt_schedule_notrace() + +#endif /* CONFIG_PREEMPT_DYNAMIC && CONFIG_HAVE_PREEMPT_DYNAMIC_KEY*/ +#endif /* CONFIG_PREEMPTION */ + +#endif /* __ASM_PREEMPT_H */ -- cgit v1.3.1