Re: [PATCH] ath9k: Fix possible data races in ath_set_channel()

Jia-Ju Bai [off-list ref] writes:

The functions ath9k_config() and ath_ani_calibrate() may be concurrently
executed.

A variable survey->filled is accessed with holding a spinlock
common->cc_lock, through:
ath_ani_calibrate()
    spin_lock_irqsave(&common->cc_lock, flags);
    ath_update_survey_stats()
        ath_update_survey_nf()
            survey->filled |= SURVEY_INFO_NOISE_DBM;

The identical variables sc->cur_survey->filled and 
sc->survey[pos].filled is accessed without holding this lock, through:
ath9k_config()
    ath_chanctx_set_channel()
        ath_set_channel()
            sc->cur_survey->filled &= ~SURVEY_INFO_IN_USE;
            sc->cur_survey->filled |= SURVEY_INFO_IN_USE;
            else if (!(sc->survey[pos].filled & SURVEY_INFO_IN_USE))
            ath_update_survey_nf
                survey->filled |= SURVEY_INFO_NOISE_DBM;

Thus, possible data races may occur.

To fix these data races, in ath_set_channel(), these variables are
accessed with holding the spinlock common->cc_lock.

These data races are found by the runtime testing of our tool DILP-2.

Signed-off-by: Jia-Ju Bai <redacted>

I need a detailed review from somone familiar with ath9k before I can
consider applying this.

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