46 lines
1.8 KiB
Diff
46 lines
1.8 KiB
Diff
https://github.com/rclone/rclone/pull/6311
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From 67fd60275a6187c41c4944545c2145cd28bc330d Mon Sep 17 00:00:00 2001
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From: r-ricci <ricci@disroot.org>
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Date: Mon, 11 Jul 2022 18:34:06 +0100
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Subject: [PATCH] union: fix panic due to misalignment of struct field in 32
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bit architectures
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`FS.cacheExpiry` is accessed through sync/atomic.
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According to the documentation, "On ARM, 386, and 32-bit MIPS, it is
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the caller's responsibility to arrange for 64-bit alignment of 64-bit
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words accessed atomically. The first word in a variable or in an
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allocated struct, array, or slice can be relied upon to be 64-bit
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aligned."
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Before commit 1d2fe0d8564bc679ece166c24b24e6fe7dc1455c this field was
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aligned, but then a new field was added to the structure, causing the
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test suite to panic on linux/386.
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No other field is used with sync/atomic, so `cacheExpiry` can just be
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placed at the beginning of the stuct to ensure it is always aligned.
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---
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backend/union/upstream/upstream.go | 5 ++++-
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1 file changed, 4 insertions(+), 1 deletion(-)
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diff --git a/backend/union/upstream/upstream.go b/backend/union/upstream/upstream.go
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index 35b477f7930a..7b9f44fd2a39 100644
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--- a/backend/union/upstream/upstream.go
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+++ b/backend/union/upstream/upstream.go
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@@ -24,6 +24,10 @@ var (
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// Fs is a wrap of any fs and its configs
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type Fs struct {
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+ // In order to ensure memory alignment on 32-bit architectures
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+ // when this field is accessed through sync/atomic functions,
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+ // it must be the first entry in the struct
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+ cacheExpiry int64 // usage cache expiry time
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fs.Fs
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RootFs fs.Fs
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RootPath string
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@@ -32,7 +36,6 @@ type Fs struct {
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creatable bool
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usage *fs.Usage // Cache the usage
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cacheTime time.Duration // cache duration
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- cacheExpiry int64 // usage cache expiry time
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cacheMutex sync.RWMutex
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cacheOnce sync.Once
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cacheUpdate bool // if the cache is updating
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