From eb449bd96954b1c1e491d19066cfd2a010f0aa47 Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Fri, 22 Nov 2024 09:44:15 -0800 Subject: mm: convert mm_lock_seq to a proper seqcount Convert mm_lock_seq to be seqcount_t and change all mmap_write_lock variants to increment it, in-line with the usual seqcount usage pattern. This lets us check whether the mmap_lock is write-locked by checking mm_lock_seq.sequence counter (odd=locked, even=unlocked). This will be used when implementing mmap_lock speculation functions. As a result vm_lock_seq is also change to be unsigned to match the type of mm_lock_seq.sequence. Suggested-by: Peter Zijlstra Signed-off-by: Suren Baghdasaryan Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Liam R. Howlett Link: https://lkml.kernel.org/r/20241122174416.1367052-2-surenb@google.com --- tools/testing/vma/vma.c | 4 ++-- tools/testing/vma/vma_internal.h | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) (limited to 'tools/testing') diff --git a/tools/testing/vma/vma.c b/tools/testing/vma/vma.c index 8fab5e13c7c3..9bcf1736bf18 100644 --- a/tools/testing/vma/vma.c +++ b/tools/testing/vma/vma.c @@ -89,7 +89,7 @@ static struct vm_area_struct *alloc_and_link_vma(struct mm_struct *mm, * begun. Linking to the tree will have caused this to be incremented, * which means we will get a false positive otherwise. */ - vma->vm_lock_seq = -1; + vma->vm_lock_seq = UINT_MAX; return vma; } @@ -214,7 +214,7 @@ static bool vma_write_started(struct vm_area_struct *vma) int seq = vma->vm_lock_seq; /* We reset after each check. */ - vma->vm_lock_seq = -1; + vma->vm_lock_seq = UINT_MAX; /* The vma_start_write() stub simply increments this value. */ return seq > -1; diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_internal.h index e76ff579e1fd..1d9fc97b8e80 100644 --- a/tools/testing/vma/vma_internal.h +++ b/tools/testing/vma/vma_internal.h @@ -241,7 +241,7 @@ struct vm_area_struct { * counter reuse can only lead to occasional unnecessary use of the * slowpath. */ - int vm_lock_seq; + unsigned int vm_lock_seq; struct vma_lock *vm_lock; #endif @@ -416,7 +416,7 @@ static inline bool vma_lock_alloc(struct vm_area_struct *vma) return false; init_rwsem(&vma->vm_lock->lock); - vma->vm_lock_seq = -1; + vma->vm_lock_seq = UINT_MAX; return true; } -- cgit v1.2.3