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    Subject[PATCH v3 20/20] x86/alternative: Comment about module removal races
    Date
    From: Nadav Amit <namit@vmware.com>

    Add a comment to clarify that users of text_poke() must ensure that
    no races with module removal take place.

    Cc: Masami Hiramatsu <mhiramat@kernel.org>
    Signed-off-by: Nadav Amit <namit@vmware.com>
    Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
    ---
    arch/x86/kernel/alternative.c | 5 +++++
    1 file changed, 5 insertions(+)

    diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
    index c63707e7ed3d..a1335b9486bf 100644
    --- a/arch/x86/kernel/alternative.c
    +++ b/arch/x86/kernel/alternative.c
    @@ -809,6 +809,11 @@ static void *__text_poke(void *addr, const void *opcode, size_t len)
    * It means the size must be writable atomically and the address must be aligned
    * in a way that permits an atomic write. It also makes sure we fit on a single
    * page.
    + *
    + * Note that the caller must ensure that if the modified code is part of a
    + * module, the module would not be removed during poking. This can be achieved
    + * by registering a module notifier, and ordering module removal and patching
    + * trough a mutex.
    */
    void *text_poke(void *addr, const void *opcode, size_t len)
    {
    --
    2.17.1
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