target/linux/ipq806x/patches-4.4/170-OPP-Allow-notifiers-to-call-dev_pm_opp_get_voltage-freq-RCU-free.patch

   1 From d330eae026b4a73e77ca0422f5cae5207d80f738 Mon Sep 17 00:00:00 2001
   2 From: Stephen Boyd <sboyd@codeaurora.org>
   3 Date: Mon, 1 Jun 2015 18:47:57 -0700
   4 Subject: OPP: Allow notifiers to call dev_pm_opp_get_{voltage, freq} RCU-free
   5
   6 We pass the dev_pm_opp structure to OPP notifiers but the users
   7 of the notifier need to surround calls to dev_pm_opp_get_*() with
   8 RCU read locks to avoid lockdep warnings. The notifier is already
   9 called with the dev_opp's srcu lock held, so it should be safe to
  10 assume the devm_pm_opp structure is already protected inside the
  11 notifier. Update the lockdep check for this.
  12
  13 Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
  14 Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
  15 ---
  16  drivers/base/power/opp/core.c | 27 +++++++++++++++------------
  17  1 file changed, 15 insertions(+), 12 deletions(-)
  18
  19 --- a/drivers/base/power/opp/core.c
  20 +++ b/drivers/base/power/opp/core.c
  21 @@ -31,9 +31,10 @@ static LIST_HEAD(dev_opp_list);
  22  /* Lock to allow exclusive modification to the device and opp lists */
  23  DEFINE_MUTEX(dev_opp_list_lock);
  24
  25 -#define opp_rcu_lockdep_assert()                                       \
  26 +#define opp_rcu_lockdep_assert(s)                                      \
  27  do {                                                                   \
  28         RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&                       \
  29 +                               !(s && srcu_read_lock_held(s)) &&       \
  30                                 !lockdep_is_held(&dev_opp_list_lock),   \
  31                            "Missing rcu_read_lock() or "                \
  32                            "dev_opp_list_lock protection");             \
  33 @@ -91,7 +92,7 @@ struct device_opp *_find_device_opp(stru
  34  {
  35         struct device_opp *dev_opp;
  36
  37 -       opp_rcu_lockdep_assert();
  38 +       opp_rcu_lockdep_assert(NULL);
  39
  40         if (IS_ERR_OR_NULL(dev)) {
  41                 pr_err("%s: Invalid parameters\n", __func__);
  42 @@ -125,10 +126,11 @@ unsigned long dev_pm_opp_get_voltage(str
  43         struct dev_pm_opp *tmp_opp;
  44         unsigned long v = 0;
  45
  46 -       opp_rcu_lockdep_assert();
  47 +       opp_rcu_lockdep_assert(&opp->dev_opp->srcu_head.srcu);
  48
  49 -       tmp_opp = rcu_dereference(opp);
  50 -       if (IS_ERR_OR_NULL(tmp_opp))
  51 +       tmp_opp = srcu_dereference_check(opp, &opp->dev_opp->srcu_head.srcu,
  52 +                                        rcu_read_lock_held());
  53 +       if (IS_ERR_OR_NULL(tmp_opp) || !tmp_opp->available)
  54                 pr_err("%s: Invalid parameters\n", __func__);
  55         else
  56                 v = tmp_opp->u_volt;
  57 @@ -157,9 +159,10 @@ unsigned long dev_pm_opp_get_freq(struct
  58         struct dev_pm_opp *tmp_opp;
  59         unsigned long f = 0;
  60
  61 -       opp_rcu_lockdep_assert();
  62 +       opp_rcu_lockdep_assert(&opp->dev_opp->srcu_head.srcu);
  63
  64 -       tmp_opp = rcu_dereference(opp);
  65 +       tmp_opp = srcu_dereference_check(opp, &opp->dev_opp->srcu_head.srcu,
  66 +                                        rcu_read_lock_held());
  67         if (IS_ERR_OR_NULL(tmp_opp) || !tmp_opp->available)
  68                 pr_err("%s: Invalid parameters\n", __func__);
  69         else
  70 @@ -191,7 +194,7 @@ bool dev_pm_opp_is_turbo(struct dev_pm_o
  71  {
  72         struct dev_pm_opp *tmp_opp;
  73
  74 -       opp_rcu_lockdep_assert();
  75 +       opp_rcu_lockdep_assert(&opp->dev_opp->srcu_head.srcu);
  76
  77         tmp_opp = rcu_dereference(opp);
  78         if (IS_ERR_OR_NULL(tmp_opp) || !tmp_opp->available) {
  79 @@ -246,7 +249,7 @@ struct dev_pm_opp *dev_pm_opp_get_suspen
  80  {
  81         struct device_opp *dev_opp;
  82
  83 -       opp_rcu_lockdep_assert();
  84 +       opp_rcu_lockdep_assert(NULL);
  85
  86         dev_opp = _find_device_opp(dev);
  87         if (IS_ERR(dev_opp) || !dev_opp->suspend_opp ||
  88 @@ -326,7 +329,7 @@ struct dev_pm_opp *dev_pm_opp_find_freq_
  89         struct device_opp *dev_opp;
  90         struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
  91
  92 -       opp_rcu_lockdep_assert();
  93 +       opp_rcu_lockdep_assert(NULL);
  94
  95         dev_opp = _find_device_opp(dev);
  96         if (IS_ERR(dev_opp)) {
  97 @@ -374,7 +377,7 @@ struct dev_pm_opp *dev_pm_opp_find_freq_
  98         struct device_opp *dev_opp;
  99         struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
 100
 101 -       opp_rcu_lockdep_assert();
 102 +       opp_rcu_lockdep_assert(NULL);
 103
 104         if (!dev || !freq) {
 105                 dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq);
 106 @@ -424,7 +427,7 @@ struct dev_pm_opp *dev_pm_opp_find_freq_
 107         struct device_opp *dev_opp;
 108         struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
 109
 110 -       opp_rcu_lockdep_assert();
 111 +       opp_rcu_lockdep_assert(NULL);
 112
 113         if (!dev || !freq) {
 114                 dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq);