From: Rafael J. Wysocki Date: Mon, 26 Sep 2011 17:40:23 +0000 (+0200) Subject: PM / Clocks: Do not acquire a mutex under a spinlock X-Git-Tag: v3.1-rc8~2^2 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e8b364b88cc4001b21c28c1ecf1e1e3ffbe162e6;p=pandora-kernel.git PM / Clocks: Do not acquire a mutex under a spinlock Commit b7ab83e (PM: Use spinlock instead of mutex in clock management functions) introduced a regression causing clocks_mutex to be acquired under a spinlock. This happens because pm_clk_suspend() and pm_clk_resume() call pm_clk_acquire() under pcd->lock, but pm_clk_acquire() executes clk_get() which causes clocks_mutex to be acquired. Similarly, __pm_clk_remove(), executed under pcd->lock, calls clk_put(), which also causes clocks_mutex to be acquired. To fix those problems make pm_clk_add() call pm_clk_acquire(), so that pm_clk_suspend() and pm_clk_resume() don't have to do that. Change pm_clk_remove() and pm_clk_destroy() to separate modifications of the pcd->clock_list list from the actual removal of PM clock entry objects done by __pm_clk_remove(). Reported-and-tested-by: Guennadi Liakhovetski Signed-off-by: Rafael J. Wysocki Acked-by: Russell King --- diff --git a/drivers/base/power/clock_ops.c b/drivers/base/power/clock_ops.c index 2c18d584066d..b97294e2d95b 100644 --- a/drivers/base/power/clock_ops.c +++ b/drivers/base/power/clock_ops.c @@ -41,6 +41,22 @@ static struct pm_clk_data *__to_pcd(struct device *dev) return dev ? dev->power.subsys_data : NULL; } +/** + * pm_clk_acquire - Acquire a device clock. + * @dev: Device whose clock is to be acquired. + * @ce: PM clock entry corresponding to the clock. + */ +static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce) +{ + ce->clk = clk_get(dev, ce->con_id); + if (IS_ERR(ce->clk)) { + ce->status = PCE_STATUS_ERROR; + } else { + ce->status = PCE_STATUS_ACQUIRED; + dev_dbg(dev, "Clock %s managed by runtime PM.\n", ce->con_id); + } +} + /** * pm_clk_add - Start using a device clock for power management. * @dev: Device whose clock is going to be used for power management. @@ -73,6 +89,8 @@ int pm_clk_add(struct device *dev, const char *con_id) } } + pm_clk_acquire(dev, ce); + spin_lock_irq(&pcd->lock); list_add_tail(&ce->node, &pcd->clock_list); spin_unlock_irq(&pcd->lock); @@ -82,17 +100,12 @@ int pm_clk_add(struct device *dev, const char *con_id) /** * __pm_clk_remove - Destroy PM clock entry. * @ce: PM clock entry to destroy. - * - * This routine must be called under the spinlock protecting the PM list of - * clocks corresponding the the @ce's device. */ static void __pm_clk_remove(struct pm_clock_entry *ce) { if (!ce) return; - list_del(&ce->node); - if (ce->status < PCE_STATUS_ERROR) { if (ce->status == PCE_STATUS_ENABLED) clk_disable(ce->clk); @@ -126,18 +139,22 @@ void pm_clk_remove(struct device *dev, const char *con_id) spin_lock_irq(&pcd->lock); list_for_each_entry(ce, &pcd->clock_list, node) { - if (!con_id && !ce->con_id) { - __pm_clk_remove(ce); - break; - } else if (!con_id || !ce->con_id) { + if (!con_id && !ce->con_id) + goto remove; + else if (!con_id || !ce->con_id) continue; - } else if (!strcmp(con_id, ce->con_id)) { - __pm_clk_remove(ce); - break; - } + else if (!strcmp(con_id, ce->con_id)) + goto remove; } spin_unlock_irq(&pcd->lock); + return; + + remove: + list_del(&ce->node); + spin_unlock_irq(&pcd->lock); + + __pm_clk_remove(ce); } /** @@ -175,43 +192,33 @@ void pm_clk_destroy(struct device *dev) { struct pm_clk_data *pcd = __to_pcd(dev); struct pm_clock_entry *ce, *c; + struct list_head list; if (!pcd) return; dev->power.subsys_data = NULL; + INIT_LIST_HEAD(&list); spin_lock_irq(&pcd->lock); list_for_each_entry_safe_reverse(ce, c, &pcd->clock_list, node) - __pm_clk_remove(ce); + list_move(&ce->node, &list); spin_unlock_irq(&pcd->lock); kfree(pcd); + + list_for_each_entry_safe_reverse(ce, c, &list, node) { + list_del(&ce->node); + __pm_clk_remove(ce); + } } #endif /* CONFIG_PM */ #ifdef CONFIG_PM_RUNTIME -/** - * pm_clk_acquire - Acquire a device clock. - * @dev: Device whose clock is to be acquired. - * @con_id: Connection ID of the clock. - */ -static void pm_clk_acquire(struct device *dev, - struct pm_clock_entry *ce) -{ - ce->clk = clk_get(dev, ce->con_id); - if (IS_ERR(ce->clk)) { - ce->status = PCE_STATUS_ERROR; - } else { - ce->status = PCE_STATUS_ACQUIRED; - dev_dbg(dev, "Clock %s managed by runtime PM.\n", ce->con_id); - } -} - /** * pm_clk_suspend - Disable clocks in a device's PM clock list. * @dev: Device to disable the clocks for. @@ -230,9 +237,6 @@ int pm_clk_suspend(struct device *dev) spin_lock_irqsave(&pcd->lock, flags); list_for_each_entry_reverse(ce, &pcd->clock_list, node) { - if (ce->status == PCE_STATUS_NONE) - pm_clk_acquire(dev, ce); - if (ce->status < PCE_STATUS_ERROR) { clk_disable(ce->clk); ce->status = PCE_STATUS_ACQUIRED; @@ -262,9 +266,6 @@ int pm_clk_resume(struct device *dev) spin_lock_irqsave(&pcd->lock, flags); list_for_each_entry(ce, &pcd->clock_list, node) { - if (ce->status == PCE_STATUS_NONE) - pm_clk_acquire(dev, ce); - if (ce->status < PCE_STATUS_ERROR) { clk_enable(ce->clk); ce->status = PCE_STATUS_ENABLED;