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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>
This commit is contained in:
Geert Uytterhoeven 2014-10-01 20:38:17 +02:00 committed by Rafael J. Wysocki
parent fe82dcec64
commit a968bed78b
1 changed files with 15 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
drivers/base/power/clock_ops.c
View File

@ -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);