Commit a968bed7 authored Oct 01, 2014 by Geert Uytterhoeven Committed by Rafael J. Wysocki Oct 03, 2014

PM / clk: Fix crash in clocks management code if !CONFIG_PM_RUNTIME



Unlike the clocks management code for runtime PM, the code used for
system suspend does not check the pm_clock_entry.status field.
If pm_clk_acquire() failed, ce->status will be PCE_STATUS_ERROR, and
ce->clk will be a negative error code (e.g. 0xfffffffe = -2 = -ENOENT).

Depending on the clock implementation, suspend or resume may crash with:

    Unable to handle kernel NULL pointer dereference at virtual address 00000026

(CCF clk_disable() has an IS_ERR_OR_NULL() check, while CCF clk_enable()
 only has a NULL check; pre-CCF implementations may behave differently)

While just checking for PCE_STATUS_ERROR would be sufficient, it doesn't
hurt to use the same state machine as is done for runtime PM, as this
makes the two versions more similar, and eligible for a future
consolidation.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

parent fe82dcec

drivers/base/power/clock_ops.c

+15 −4

Original line number	Diff line number	Diff line
		@@ -368,8 +368,13 @@ int pm_clk_suspend(struct device *dev)

		spin_lock_irqsave(&psd->lock, flags);

		list_for_each_entry_reverse(ce, &psd->clock_list, node)
		list_for_each_entry_reverse(ce, &psd->clock_list, node) {
		if (ce->status < PCE_STATUS_ERROR) {
		if (ce->status == PCE_STATUS_ENABLED)
		clk_disable(ce->clk);
		ce->status = PCE_STATUS_ACQUIRED;
		}
		}

		spin_unlock_irqrestore(&psd->lock, flags);

		@@ -385,6 +390,7 @@ int pm_clk_resume(struct device *dev)
		struct pm_subsys_data *psd = dev_to_psd(dev);
		struct pm_clock_entry *ce;
		unsigned long flags;
		int ret;

		dev_dbg(dev, "%s()\n", __func__);

		@@ -394,8 +400,13 @@ int pm_clk_resume(struct device *dev)

		spin_lock_irqsave(&psd->lock, flags);

		list_for_each_entry(ce, &psd->clock_list, node)
		__pm_clk_enable(dev, ce->clk);
		list_for_each_entry(ce, &psd->clock_list, node) {
		if (ce->status < PCE_STATUS_ERROR) {
		ret = __pm_clk_enable(dev, ce->clk);
		if (!ret)
		ce->status = PCE_STATUS_ENABLED;
		}
		}

		spin_unlock_irqrestore(&psd->lock, flags);