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wil6210: protect wil_vring_fini_tx in parallel to tx completions

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napi_synchronize is called before releasing the vring, with the
assumption that setting txdata->enabled to 0 will prevent handling
of this vring in the next scheduled napi.
To guarantee this assumption, a memory barrier is added after disabling
the txdata.
In addition, as the ctx is zeroed in wil_tx_complete after this
descriptor is handled (protected by wmb), ctx needs to be checked
before releasing this descriptor in wil_vring_free.

Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
This commit is contained in:
Maya Erez 2016-05-16 22:23:32 +03:00 committed by Kalle Valo
parent ab6d7cc3ea
commit 34b8886e50
1 changed files with 14 additions and 0 deletions
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14
drivers/net/wireless/ath/wil6210/txrx.c
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@ -184,6 +184,13 @@ static void wil_vring_free(struct wil6210_priv *wil, struct vring *vring,
&vring->va[vring->swtail].tx;
ctx = &vring->ctx[vring->swtail];
if (!ctx) {
wil_dbg_txrx(wil,
"ctx(%d) was already completed\n",
vring->swtail);
vring->swtail = wil_vring_next_tail(vring);
continue;
}
*d = *_d;
wil_txdesc_unmap(dev, d, ctx);
if (ctx->skb)
@ -975,6 +982,13 @@ void wil_vring_fini_tx(struct wil6210_priv *wil, int id)
txdata->dot1x_open = false;
txdata->enabled = 0; /* no Tx can be in progress or start anew */
spin_unlock_bh(&txdata->lock);
/* napi_synchronize waits for completion of the current NAPI but will
* not prevent the next NAPI run.
* Add a memory barrier to guarantee that txdata->enabled is zeroed
* before napi_synchronize so that the next scheduled NAPI will not
* handle this vring
*/
wmb();
/* make sure NAPI won't touch this vring */
if (test_bit(wil_status_napi_en, wil->status))
napi_synchronize(&wil->napi_tx);