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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Johannes Berg <johannes.berg@intel.com>,
        Luca Coelho <luciano.coelho@intel.com>,
        Kalle Valo <kvalo@codeaurora.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 13/24] iwlwifi: mvm: guard against device removal in reprobe
Date:   Thu, 11 Feb 2021 16:02:47 +0100
Message-Id: <20210211150148.335575799@linuxfoundation.org>
In-Reply-To: <20210211150147.743660073@linuxfoundation.org>
References: <20210211150147.743660073@linuxfoundation.org>
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From: Johannes Berg <johannes.berg@intel.com>

[ Upstream commit 7a21b1d4a728a483f07c638ccd8610d4b4f12684 ]

If we get into a problem severe enough to attempt a reprobe,
we schedule a worker to do that. However, if the problem gets
more severe and the device is actually destroyed before this
worker has a chance to run, we use a free device. Bump up the
reference count of the device until the worker runs to avoid
this situation.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/iwlwifi.20210122144849.871f0892e4b2.I94819e11afd68d875f3e242b98bef724b8236f1e@changeid
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/wireless/intel/iwlwifi/mvm/ops.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/ops.c b/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
index 0e26619fb330b..d932171617e6a 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
@@ -1192,6 +1192,7 @@ static void iwl_mvm_reprobe_wk(struct work_struct *wk)
 	reprobe = container_of(wk, struct iwl_mvm_reprobe, work);
 	if (device_reprobe(reprobe->dev))
 		dev_err(reprobe->dev, "reprobe failed!\n");
+	put_device(reprobe->dev);
 	kfree(reprobe);
 	module_put(THIS_MODULE);
 }
@@ -1242,7 +1243,7 @@ void iwl_mvm_nic_restart(struct iwl_mvm *mvm, bool fw_error)
 			module_put(THIS_MODULE);
 			return;
 		}
-		reprobe->dev = mvm->trans->dev;
+		reprobe->dev = get_device(mvm->trans->dev);
 		INIT_WORK(&reprobe->work, iwl_mvm_reprobe_wk);
 		schedule_work(&reprobe->work);
 	} else if (mvm->fwrt.cur_fw_img == IWL_UCODE_REGULAR &&
-- 
2.27.0