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authorDavid Lechner <david@lechnology.com>2018-01-04 19:46:08 -0600
committerStephen Boyd <sboyd@codeaurora.org>2018-01-10 13:39:31 -0800
commita12aa8a68dfef5de181f2e555aa950a0ab05411f (patch)
treef2faf66b671c503e15028be86a07e70f63767f96 /drivers/clk
parent4fbd8d194f06c8a3fd2af1ce560ddb31f7ec8323 (diff)
clk: fix reentrancy of clk_enable() on UP systems
Reentrant calls to clk_enable() are not working on UP systems. This is caused by the fact spin_trylock_irqsave() always returns true when CONFIG_SMP=n (and CONFIG_DEBUG_SPINLOCK=n) which causes the reference counting to not work correctly when clk_enable_lock() is called twice before clk_enable_unlock() is called (this happens when clk_enable() is called from within another clk_enable()). This fixes the problem by skipping the call to spin_trylock_irqsave() on UP systems and relying solely on reference counting. We also make sure to set flags in this case so that we are not returning an uninitialized value. Suggested-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: David Lechner <david@lechnology.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Diffstat (limited to 'drivers/clk')
-rw-r--r--drivers/clk/clk.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 647d056df88c..b221d80cc7ba 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -141,10 +141,18 @@ static unsigned long clk_enable_lock(void)
{
unsigned long flags;
- if (!spin_trylock_irqsave(&enable_lock, flags)) {
+ /*
+ * On UP systems, spin_trylock_irqsave() always returns true, even if
+ * we already hold the lock. So, in that case, we rely only on
+ * reference counting.
+ */
+ if (!IS_ENABLED(CONFIG_SMP) ||
+ !spin_trylock_irqsave(&enable_lock, flags)) {
if (enable_owner == current) {
enable_refcnt++;
__acquire(enable_lock);
+ if (!IS_ENABLED(CONFIG_SMP))
+ local_save_flags(flags);
return flags;
}
spin_lock_irqsave(&enable_lock, flags);

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