From 0efe289db5f67e753763797be32c28c1ce43daf2 Mon Sep 17 00:00:00 2001 From: "Poddar, Siddarth" Date: Tue, 18 Jul 2017 16:10:07 +0530 Subject: [PATCH] qcacmn: Perform napi state comparison before releasing napi lock Release napi spinlock only after performing napi state comparison to avoid any race condition. Change-Id: Icd7b713e474a818dfc6d0fa402496bbe06a3af66 CRs-Fixed: 2078294 --- hif/src/hif_napi.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/hif/src/hif_napi.c b/hif/src/hif_napi.c index e2a423621b52..8528b2d8933f 100644 --- a/hif/src/hif_napi.c +++ b/hif/src/hif_napi.c @@ -410,6 +410,7 @@ int hif_napi_event(struct hif_opaque_softc *hif_ctx, enum qca_napi_event event, int rc = 0; uint32_t prev_state; int i; + bool state_changed; struct napi_struct *napi; struct hif_softc *hif = HIF_GET_SOFTC(hif_ctx); struct qca_napi_data *napid = &(hif->napi_data); @@ -559,9 +560,18 @@ int hif_napi_event(struct hif_opaque_softc *hif_ctx, enum qca_napi_event event, break; } /* switch blacklist_pending */ + /* we want to perform the comparison in lock: + * there is a possiblity of hif_napi_event get called + * from two different contexts (driver unload and cpu hotplug + * notification) and napid->state get changed + * in driver unload context and can lead to race condition + * in cpu hotplug context. Therefore, perform the napid->state + * comparison before releasing lock. + */ + state_changed = (prev_state != napid->state); qdf_spin_unlock_bh(&(napid->lock)); - if (prev_state != napid->state) { + if (state_changed) { if (napid->state == ENABLE_NAPI_MASK) { rc = 1; for (i = 0; i < CE_COUNT_MAX; i++) {