dmaengine: shdma: synchronize RCU before freeing, simplify spinlock
Guennadi Liakhovetski [Mon, 2 May 2011 07:59:02 +0000 (07:59 +0000)]
List elements, deleted using list_del_rcu(), cannot be freed without
synchronising RCU. Further, the spinlock, used to protect the RCU
writer, is called in process context, so, we don't have to save flags.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

drivers/dma/shdma.c

index 00b5f32..dcc1b21 100644 (file)
@@ -1077,7 +1077,6 @@ static int __init sh_dmae_probe(struct platform_device *pdev)
        struct sh_dmae_pdata *pdata = pdev->dev.platform_data;
        unsigned long irqflags = IRQF_DISABLED,
                chan_flag[SH_DMAC_MAX_CHANNELS] = {};
-       unsigned long flags;
        int errirq, chan_irq[SH_DMAC_MAX_CHANNELS];
        int err, i, irq_cnt = 0, irqres = 0;
        struct sh_dmae_device *shdev;
@@ -1143,9 +1142,9 @@ static int __init sh_dmae_probe(struct platform_device *pdev)
        pm_runtime_enable(&pdev->dev);
        pm_runtime_get_sync(&pdev->dev);
 
-       spin_lock_irqsave(&sh_dmae_lock, flags);
+       spin_lock_irq(&sh_dmae_lock);
        list_add_tail_rcu(&shdev->node, &sh_dmae_devices);
-       spin_unlock_irqrestore(&sh_dmae_lock, flags);
+       spin_unlock_irq(&sh_dmae_lock);
 
        /* reset dma controller - only needed as a test */
        err = sh_dmae_rst(shdev);
@@ -1250,9 +1249,9 @@ eirqres:
 eirq_err:
 #endif
 rst_err:
-       spin_lock_irqsave(&sh_dmae_lock, flags);
+       spin_lock_irq(&sh_dmae_lock);
        list_del_rcu(&shdev->node);
-       spin_unlock_irqrestore(&sh_dmae_lock, flags);
+       spin_unlock_irq(&sh_dmae_lock);
 
        pm_runtime_put(&pdev->dev);
        pm_runtime_disable(&pdev->dev);
@@ -1261,6 +1260,7 @@ rst_err:
                iounmap(shdev->dmars);
 emapdmars:
        iounmap(shdev->chan_reg);
+       synchronize_rcu();
 emapchan:
        kfree(shdev);
 ealloc:
@@ -1276,7 +1276,6 @@ static int __exit sh_dmae_remove(struct platform_device *pdev)
 {
        struct sh_dmae_device *shdev = platform_get_drvdata(pdev);
        struct resource *res;
-       unsigned long flags;
        int errirq = platform_get_irq(pdev, 0);
 
        dma_async_device_unregister(&shdev->common);
@@ -1284,9 +1283,9 @@ static int __exit sh_dmae_remove(struct platform_device *pdev)
        if (errirq > 0)
                free_irq(errirq, shdev);
 
-       spin_lock_irqsave(&sh_dmae_lock, flags);
+       spin_lock_irq(&sh_dmae_lock);
        list_del_rcu(&shdev->node);
-       spin_unlock_irqrestore(&sh_dmae_lock, flags);
+       spin_unlock_irq(&sh_dmae_lock);
 
        /* channel data remove */
        sh_dmae_chan_remove(shdev);
@@ -1297,6 +1296,7 @@ static int __exit sh_dmae_remove(struct platform_device *pdev)
                iounmap(shdev->dmars);
        iounmap(shdev->chan_reg);
 
+       synchronize_rcu();
        kfree(shdev);
 
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);