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>

diff --git a/drivers/base/power/clock_ops.c b/drivers/base/power/clock_ops.c
index b99e6c0..7836930 100644 (file)
--- a/drivers/base/power/clock_ops.c
+++ b/drivers/base/power/clock_ops.c
@@ -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)
-               clk_disable(ce->clk);
+       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);