[PATCH 08/11] crypto: ccree - fix PM race condition - Gilad Ben-Yossef

From: Gilad Ben-Yossef <gilad@benyossef.com>
To: Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>
Cc: Ofir Drang <ofir.drang@arm.com>, Hadar Gat <hadar.gat@arm.com>,
	stable@kernel.org, linux-crypto@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 08/11] crypto: ccree - fix PM race condition
Date: Thu, 16 Jan 2020 12:14:43 +0200	[thread overview]
Message-ID: <20200116101447.20374-9-gilad@benyossef.com> (raw)
In-Reply-To: <20200116101447.20374-1-gilad@benyossef.com>

The PM code was racy, possibly causing the driver to submit
requests to a powered down device. Fix the race and while
at it simplify the PM code.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Fixes: 1358c13a48c4 ("crypto: ccree - fix resume race condition on init")
Cc: stable@kernel.org # v4.20
---
 drivers/crypto/ccree/cc_driver.h      |  1 +
 drivers/crypto/ccree/cc_pm.c          | 28 ++++-----------
 drivers/crypto/ccree/cc_request_mgr.c | 50 ---------------------------
 drivers/crypto/ccree/cc_request_mgr.h |  8 -----
 4 files changed, 7 insertions(+), 80 deletions(-)

diff --git a/drivers/crypto/ccree/cc_driver.h b/drivers/crypto/ccree/cc_driver.h
index 7b6b5d6f1b33..9d77cfdb10d9 100644
--- a/drivers/crypto/ccree/cc_driver.h
+++ b/drivers/crypto/ccree/cc_driver.h
@@ -160,6 +160,7 @@ struct cc_drvdata {
 	int std_bodies;
 	bool sec_disabled;
 	u32 comp_mask;
+	bool pm_on;
 };
 
 struct cc_crypto_alg {
diff --git a/drivers/crypto/ccree/cc_pm.c b/drivers/crypto/ccree/cc_pm.c
index 79c612144310..ee9e9cba2fbb 100644
--- a/drivers/crypto/ccree/cc_pm.c
+++ b/drivers/crypto/ccree/cc_pm.c
@@ -22,14 +22,8 @@ const struct dev_pm_ops ccree_pm = {
 int cc_pm_suspend(struct device *dev)
 {
 	struct cc_drvdata *drvdata = dev_get_drvdata(dev);
-	int rc;
 
 	dev_dbg(dev, "set HOST_POWER_DOWN_EN\n");
-	rc = cc_suspend_req_queue(drvdata);
-	if (rc) {
-		dev_err(dev, "cc_suspend_req_queue (%x)\n", rc);
-		return rc;
-	}
 	fini_cc_regs(drvdata);
 	cc_iowrite(drvdata, CC_REG(HOST_POWER_DOWN_EN), POWER_DOWN_ENABLE);
 	cc_clk_off(drvdata);
@@ -63,13 +57,6 @@ int cc_pm_resume(struct device *dev)
 	/* check if tee fips error occurred during power down */
 	cc_tee_handle_fips_error(drvdata);
 
-	rc = cc_resume_req_queue(drvdata);
-	if (rc) {
-		dev_err(dev, "cc_resume_req_queue (%x)\n", rc);
-		return rc;
-	}
-
-	/* must be after the queue resuming as it uses the HW queue*/
 	cc_init_hash_sram(drvdata);
 
 	return 0;
@@ -80,10 +67,8 @@ int cc_pm_get(struct device *dev)
 	int rc = 0;
 	struct cc_drvdata *drvdata = dev_get_drvdata(dev);
 
-	if (cc_req_queue_suspended(drvdata))
+	if (drvdata->pm_on)
 		rc = pm_runtime_get_sync(dev);
-	else
-		pm_runtime_get_noresume(dev);
 
 	return (rc == 1 ? 0 : rc);
 }
@@ -93,14 +78,11 @@ int cc_pm_put_suspend(struct device *dev)
 	int rc = 0;
 	struct cc_drvdata *drvdata = dev_get_drvdata(dev);
 
-	if (!cc_req_queue_suspended(drvdata)) {
+	if (drvdata->pm_on) {
 		pm_runtime_mark_last_busy(dev);
 		rc = pm_runtime_put_autosuspend(dev);
-	} else {
-		/* Something wrong happens*/
-		dev_err(dev, "request to suspend already suspended queue");
-		rc = -EBUSY;
 	}
+
 	return rc;
 }
 
@@ -117,7 +99,7 @@ int cc_pm_init(struct cc_drvdata *drvdata)
 	/* must be before the enabling to avoid redundant suspending */
 	pm_runtime_set_autosuspend_delay(dev, CC_SUSPEND_TIMEOUT);
 	pm_runtime_use_autosuspend(dev);
-	/* activate the PM module */
+	/* set us as active - note we won't do PM ops until cc_pm_go()! */
 	return pm_runtime_set_active(dev);
 }
 
@@ -125,9 +107,11 @@ int cc_pm_init(struct cc_drvdata *drvdata)
 void cc_pm_go(struct cc_drvdata *drvdata)
 {
 	pm_runtime_enable(drvdata_to_dev(drvdata));
+	drvdata->pm_on = true;
 }
 
 void cc_pm_fini(struct cc_drvdata *drvdata)
 {
 	pm_runtime_disable(drvdata_to_dev(drvdata));
+	drvdata->pm_on = false;
 }
diff --git a/drivers/crypto/ccree/cc_request_mgr.c b/drivers/crypto/ccree/cc_request_mgr.c
index ce09c430c8b9..9d61e6f12478 100644
--- a/drivers/crypto/ccree/cc_request_mgr.c
+++ b/drivers/crypto/ccree/cc_request_mgr.c
@@ -41,7 +41,6 @@ struct cc_req_mgr_handle {
 #else
 	struct tasklet_struct comptask;
 #endif
-	bool is_runtime_suspended;
 };
 
 struct cc_bl_item {
@@ -664,52 +663,3 @@ static void comp_handler(unsigned long devarg)
 	cc_proc_backlog(drvdata);
 	dev_dbg(dev, "Comp. handler done.\n");
 }
-
-/*
- * resume the queue configuration - no need to take the lock as this happens
- * inside the spin lock protection
- */
-#if defined(CONFIG_PM)
-int cc_resume_req_queue(struct cc_drvdata *drvdata)
-{
-	struct cc_req_mgr_handle *request_mgr_handle =
-		drvdata->request_mgr_handle;
-
-	spin_lock_bh(&request_mgr_handle->hw_lock);
-	request_mgr_handle->is_runtime_suspended = false;
-	spin_unlock_bh(&request_mgr_handle->hw_lock);
-
-	return 0;
-}
-
-/*
- * suspend the queue configuration. Since it is used for the runtime suspend
- * only verify that the queue can be suspended.
- */
-int cc_suspend_req_queue(struct cc_drvdata *drvdata)
-{
-	struct cc_req_mgr_handle *request_mgr_handle =
-						drvdata->request_mgr_handle;
-
-	/* lock the send_request */
-	spin_lock_bh(&request_mgr_handle->hw_lock);
-	if (request_mgr_handle->req_queue_head !=
-	    request_mgr_handle->req_queue_tail) {
-		spin_unlock_bh(&request_mgr_handle->hw_lock);
-		return -EBUSY;
-	}
-	request_mgr_handle->is_runtime_suspended = true;
-	spin_unlock_bh(&request_mgr_handle->hw_lock);
-
-	return 0;
-}
-
-bool cc_req_queue_suspended(struct cc_drvdata *drvdata)
-{
-	struct cc_req_mgr_handle *request_mgr_handle =
-						drvdata->request_mgr_handle;
-
-	return	request_mgr_handle->is_runtime_suspended;
-}
-
-#endif
diff --git a/drivers/crypto/ccree/cc_request_mgr.h b/drivers/crypto/ccree/cc_request_mgr.h
index f46cf766fe4d..ff7746aaaf35 100644
--- a/drivers/crypto/ccree/cc_request_mgr.h
+++ b/drivers/crypto/ccree/cc_request_mgr.h
@@ -40,12 +40,4 @@ void complete_request(struct cc_drvdata *drvdata);
 
 void cc_req_mgr_fini(struct cc_drvdata *drvdata);
 
-#if defined(CONFIG_PM)
-int cc_resume_req_queue(struct cc_drvdata *drvdata);
-
-int cc_suspend_req_queue(struct cc_drvdata *drvdata);
-
-bool cc_req_queue_suspended(struct cc_drvdata *drvdata);
-#endif
-
 #endif /*__REQUEST_MGR_H__*/
-- 
2.23.0

