[GitHub] [mynewt-nffs] yashi opened a new issue #19: Infinite loop in nffs_gc()

[GitBox <gi...@apache.org>]

yashi opened a new issue #19: Infinite loop in nffs_gc()
URL: https://github.com/apache/mynewt-nffs/issues/19
 
 
   This is a classic "Do not reorder while traversing a list" bug from the `nffs_hash` in `nffs_gc()`.
   
   In the while-loop to traverse `nffs_hash` list in `nffs_gc()`, we call `nffs_gc_inode_blocks()`. But `nffs_gc_inode_blocks()` reorders the given list when GC. If the reorder puts the current node back to previous, then call nffs_gc_inode_blocks() again, it will inf loop.
   
   That is, say we have a list of A->B->C->D. while we are at C, we call nffs_gc_inode_blocks(). The function can reorder the list to A->C->B->D. Now we process B, and call nffs_gc_inode_blocks(). This time the function reorder the list back to to A->B->C->D. The next node is C again. C call the func, and get A->C->B->D. The next is B. Call the func. Get A->B->C->D. Then next is C. And B, and C, B, C, B, C, B, C.... Inf loop.

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