diff options
| author | David Lechner <david@lechnology.com> | 2018-01-04 19:46:08 -0600 |
|---|---|---|
| committer | Stephen Boyd <sboyd@codeaurora.org> | 2018-01-10 13:39:31 -0800 |
| commit | a12aa8a68dfef5de181f2e555aa950a0ab05411f (patch) | |
| tree | f2faf66b671c503e15028be86a07e70f63767f96 /drivers/clk/clk.c | |
| parent | 4fbd8d194f06c8a3fd2af1ce560ddb31f7ec8323 (diff) | |
| download | linux-a12aa8a68dfef5de181f2e555aa950a0ab05411f.tar.bz2 | |
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/clk.c')
| -rw-r--r-- | drivers/clk/clk.c | 10 |
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); |