All of lore.kernel.org
 help / color / mirror / Atom feed
From: Arnd Bergmann <arnd@arndb.de>
To: Jani Nikula <jani.nikula@linux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	David Airlie <airlied@linux.ie>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Tvrtko Ursulin <tvrtko.ursulin@intel.com>,
	Chris Wilson <chris@chris-wilson.co.uk>,
	Michal Wajdeczko <michal.wajdeczko@intel.com>,
	intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH] drm/i915/pmu: avoid -Wmaybe-uninitialized warning
Date: Tue, 13 Mar 2018 13:08:29 +0100	[thread overview]
Message-ID: <20180313120848.2658626-1-arnd@arndb.de> (raw)

The conditional spinlock confuses gcc into thinking the 'flags' value
might contain uninitialized data:

drivers/gpu/drm/i915/i915_pmu.c: In function '__i915_pmu_event_read':
arch/x86/include/asm/paravirt_types.h:573:3: error: 'flags' may be used uninitialized in this function [-Werror=maybe-uninitialized]

The code is correct, but it's easy to see how the compiler gets confused
here. This avoids the problem by pulling the lock outside of the function
into its only caller.

Fixes: 1fe699e30113 ("drm/i915/pmu: Fix sleep under atomic in RC6 readout")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/gpu/drm/i915/i915_pmu.c | 25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 4bc7aefa9541..2c8c705d1f18 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -415,7 +415,6 @@ static u64 __get_rc6(struct drm_i915_private *i915)
 static u64 get_rc6(struct drm_i915_private *i915, bool locked)
 {
 #if IS_ENABLED(CONFIG_PM)
-	unsigned long flags;
 	u64 val;
 
 	if (intel_runtime_pm_get_if_in_use(i915)) {
@@ -428,18 +427,12 @@ static u64 get_rc6(struct drm_i915_private *i915, bool locked)
 		 * previously.
 		 */
 
-		if (!locked)
-			spin_lock_irqsave(&i915->pmu.lock, flags);
-
 		if (val >= i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur) {
 			i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur = 0;
 			i915->pmu.sample[__I915_SAMPLE_RC6].cur = val;
 		} else {
 			val = i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur;
 		}
-
-		if (!locked)
-			spin_unlock_irqrestore(&i915->pmu.lock, flags);
 	} else {
 		struct pci_dev *pdev = i915->drm.pdev;
 		struct device *kdev = &pdev->dev;
@@ -452,9 +445,6 @@ static u64 get_rc6(struct drm_i915_private *i915, bool locked)
 		 * on top of the last known real value, as the approximated RC6
 		 * counter value.
 		 */
-		if (!locked)
-			spin_lock_irqsave(&i915->pmu.lock, flags);
-
 		spin_lock_irqsave(&kdev->power.lock, flags2);
 
 		if (!i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur)
@@ -470,9 +460,6 @@ static u64 get_rc6(struct drm_i915_private *i915, bool locked)
 		val = jiffies_to_nsecs(val);
 		val += i915->pmu.sample[__I915_SAMPLE_RC6].cur;
 		i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur = val;
-
-		if (!locked)
-			spin_unlock_irqrestore(&i915->pmu.lock, flags);
 	}
 
 	return val;
@@ -519,8 +506,16 @@ static u64 __i915_pmu_event_read(struct perf_event *event, bool locked)
 			val = count_interrupts(i915);
 			break;
 		case I915_PMU_RC6_RESIDENCY:
-			val = get_rc6(i915, locked);
-			break;
+			if (!locked) {
+				unsigned long flags;
+
+				spin_lock_irqsave(&i915->pmu.lock, flags);
+				val = get_rc6(i915, locked);
+				spin_unlock_irqrestore(&i915->pmu.lock, flags);
+				break;
+			} else {
+				val = get_rc6(i915, locked);
+			}
 		}
 	}
 
-- 
2.9.0

WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: Jani Nikula <jani.nikula@linux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	David Airlie <airlied@linux.ie>
Cc: Arnd Bergmann <arnd@arndb.de>,
	intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org
Subject: [PATCH] drm/i915/pmu: avoid -Wmaybe-uninitialized warning
Date: Tue, 13 Mar 2018 13:08:29 +0100	[thread overview]
Message-ID: <20180313120848.2658626-1-arnd@arndb.de> (raw)

The conditional spinlock confuses gcc into thinking the 'flags' value
might contain uninitialized data:

drivers/gpu/drm/i915/i915_pmu.c: In function '__i915_pmu_event_read':
arch/x86/include/asm/paravirt_types.h:573:3: error: 'flags' may be used uninitialized in this function [-Werror=maybe-uninitialized]

The code is correct, but it's easy to see how the compiler gets confused
here. This avoids the problem by pulling the lock outside of the function
into its only caller.

Fixes: 1fe699e30113 ("drm/i915/pmu: Fix sleep under atomic in RC6 readout")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/gpu/drm/i915/i915_pmu.c | 25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 4bc7aefa9541..2c8c705d1f18 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -415,7 +415,6 @@ static u64 __get_rc6(struct drm_i915_private *i915)
 static u64 get_rc6(struct drm_i915_private *i915, bool locked)
 {
 #if IS_ENABLED(CONFIG_PM)
-	unsigned long flags;
 	u64 val;
 
 	if (intel_runtime_pm_get_if_in_use(i915)) {
@@ -428,18 +427,12 @@ static u64 get_rc6(struct drm_i915_private *i915, bool locked)
 		 * previously.
 		 */
 
-		if (!locked)
-			spin_lock_irqsave(&i915->pmu.lock, flags);
-
 		if (val >= i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur) {
 			i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur = 0;
 			i915->pmu.sample[__I915_SAMPLE_RC6].cur = val;
 		} else {
 			val = i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur;
 		}
-
-		if (!locked)
-			spin_unlock_irqrestore(&i915->pmu.lock, flags);
 	} else {
 		struct pci_dev *pdev = i915->drm.pdev;
 		struct device *kdev = &pdev->dev;
@@ -452,9 +445,6 @@ static u64 get_rc6(struct drm_i915_private *i915, bool locked)
 		 * on top of the last known real value, as the approximated RC6
 		 * counter value.
 		 */
-		if (!locked)
-			spin_lock_irqsave(&i915->pmu.lock, flags);
-
 		spin_lock_irqsave(&kdev->power.lock, flags2);
 
 		if (!i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur)
@@ -470,9 +460,6 @@ static u64 get_rc6(struct drm_i915_private *i915, bool locked)
 		val = jiffies_to_nsecs(val);
 		val += i915->pmu.sample[__I915_SAMPLE_RC6].cur;
 		i915->pmu.sample[__I915_SAMPLE_RC6_ESTIMATED].cur = val;
-
-		if (!locked)
-			spin_unlock_irqrestore(&i915->pmu.lock, flags);
 	}
 
 	return val;
@@ -519,8 +506,16 @@ static u64 __i915_pmu_event_read(struct perf_event *event, bool locked)
 			val = count_interrupts(i915);
 			break;
 		case I915_PMU_RC6_RESIDENCY:
-			val = get_rc6(i915, locked);
-			break;
+			if (!locked) {
+				unsigned long flags;
+
+				spin_lock_irqsave(&i915->pmu.lock, flags);
+				val = get_rc6(i915, locked);
+				spin_unlock_irqrestore(&i915->pmu.lock, flags);
+				break;
+			} else {
+				val = get_rc6(i915, locked);
+			}
 		}
 	}
 
-- 
2.9.0

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

             reply	other threads:[~2018-03-13 12:09 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-13 12:08 Arnd Bergmann [this message]
2018-03-13 12:08 ` [PATCH] drm/i915/pmu: avoid -Wmaybe-uninitialized warning Arnd Bergmann
2018-03-13 12:29 ` ✗ Fi.CI.SPARSE: warning for " Patchwork
2018-03-13 12:49   ` Arnd Bergmann
2018-03-13 12:31 ` [PATCH] " Chris Wilson
2018-03-13 12:31   ` Chris Wilson
2018-03-13 12:55   ` Arnd Bergmann
2018-03-13 12:55     ` Arnd Bergmann
2018-03-13 12:53 ` ✓ Fi.CI.BAT: success for " Patchwork
2018-03-13 14:41 ` ✓ Fi.CI.IGT: " Patchwork

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180313120848.2658626-1-arnd@arndb.de \
    --to=arnd@arndb.de \
    --cc=airlied@linux.ie \
    --cc=chris@chris-wilson.co.uk \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=intel-gfx@lists.freedesktop.org \
    --cc=jani.nikula@linux.intel.com \
    --cc=joonas.lahtinen@linux.intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=michal.wajdeczko@intel.com \
    --cc=rodrigo.vivi@intel.com \
    --cc=tvrtko.ursulin@intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.