On 4/14/2020 12:48 PM, Viresh Kumar wrote:
On 14-04-20, 12:45, Rajendra Nayak wrote:
Fixup dev_pm_opp_put_clkname() to check for a valid clock pointer
before it does a clk_put, since its likely that
_opp_table_kref_release() has already done a clk_put. Also fixup
kref release is the last thing that happens on the table, it can't get
called after dev_pm_opp_put_clkname().
so in cases where I do have an OPP table for a device in DT and I do
dev_pm_opp_set_clkname()
dev_pm_opp_of_add_table()
and clean it up with a
dev_pm_opp_of_remove_table()
dev_pm_opp_put_clkname()
things seem to work fine as expected.
However, given I call these unconditionally in common drivers and on
some (old) platforms we really don't have an OPP table (only scale clocks)
things get a little tricky. So looks like the ref counting in such cases
gets messed up, and we end up with dev_pm_opp_of_remove_table() calling
_opp_table_kref_release() and releasing the clock, and then the subsequent
call to dev_pm_opp_put_clkname() crashes.
_opp_table_kref_release() to set the clock pointer to ERR_PTR(-EINVAL)
after its done doing a clk_put so dev_pm_opp_put_clkname() can then
catch it.
Signed-off-by: Rajendra Nayak <rnayak@xxxxxxxxxxxxxx>
---
drivers/opp/core.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index e4f01e7..6d064a8 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1061,8 +1061,10 @@ static void _opp_table_kref_release(struct kref *kref)
_of_clear_opp_table(opp_table);
/* Release clk */
- if (!IS_ERR(opp_table->clk))
+ if (!IS_ERR(opp_table->clk)) {
clk_put(opp_table->clk);
+ opp_table->clk = ERR_PTR(-EINVAL);
+ }
WARN_ON(!list_empty(&opp_table->opp_list));
@@ -1744,8 +1746,10 @@ void dev_pm_opp_put_clkname(struct opp_table *opp_table)
/* Make sure there are no concurrent readers while updating opp_table */
WARN_ON(!list_empty(&opp_table->opp_list));
- clk_put(opp_table->clk);
- opp_table->clk = ERR_PTR(-EINVAL);
+ if (!IS_ERR(opp_table->clk)) {
+ clk_put(opp_table->clk);
+ opp_table->clk = ERR_PTR(-EINVAL);
+ }
dev_pm_opp_put_opp_table(opp_table);
}
--
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--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation
