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    SubjectRe: [PATCH] tracing/lockdep: turn lock->name into an array

    * KOSAKI Motohiro <> wrote:

    > Hi
    > > Impact: allow filtering by lock name / fix module tracing
    > >
    > > Currently, the "lock acquired" event is traced using a TRACE_EVENT.
    > > But we can't use the char * type for the name without risking to
    > > dereference a freed pointer. A lock name can come from a module
    > > towards lockdep and it is risky to only store its address because we
    > > defer its name printing.
    > When released lockdep string table? I guess it only happend at
    > module unloading. if so, we should consider to make delayed string
    > table freeing at module unloading.
    > My point is, module unloading is rare event. thus meking pointer
    > safe mechanism widely avoid string copy.
    > IOW, if not, ringbuffer is filled tons string. it kill the merit
    > of binary buffer and current design.

    We could zap all pending trace entries on module unload (it is a
    rare operation). That would indeed make a whole category of
    symbol-alike string pointers safe to be passed by value.


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