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This patch checks all the calls to dst_hold()/skb_dst_force()/dst_clone()/dst_use() to see if dst_hold_safe() is needed to avoid double free issue if dst gc is removed and dst_release() directly destroys dst when dst->__refcnt drops to 0. In tx path, TCP hold sk->sk_rx_dst ref count and also hold sock_lock(). UDP and other similar protocols always hold refcount for skb->_skb_refdst. So both paths seem to be safe. In rx path, as it is lockless and skb_dst_set_noref() is likely to be used, dst_hold_safe() should always be used when trying to hold dst. In the routing code, if dst is held during an rcu protected session, it is necessary to call dst_hold_safe() as the current dst might be in its rcu grace period. Signed-off-by: Wei Wang <weiwan@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.