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OPP: fix dev_pm_opp_find_bw_*() when bandwidth table not initialized

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If a driver calls dev_pm_opp_find_bw_ceil/floor() the retrieve bandwidth
from the OPP table but the bandwidth table was not created because the
interconnect properties were missing in the OPP consumer node, the
kernel will crash with:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004
...
pc : _read_bw+0x8/0x10
lr : _opp_table_find_key+0x9c/0x174
...
Call trace:
  _read_bw+0x8/0x10 (P)
  _opp_table_find_key+0x9c/0x174 (L)
  _find_key+0x98/0x168
  dev_pm_opp_find_bw_ceil+0x50/0x88
...

In order to fix the crash, create an assert function to check
if the bandwidth table was created before trying to get a
bandwidth with _read_bw().

Fixes: add1dc094a ("OPP: Use generic key finding helpers for bandwidth key")
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
This commit is contained in:
Neil Armstrong 2024-12-03 09:13:00 +01:00 committed by Viresh Kumar
parent 964f28cdc0
commit e0460b08c6
1 changed files with 13 additions and 2 deletions
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15
drivers/opp/core.c
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@ -116,6 +116,15 @@ static bool assert_clk_index(struct opp_table *opp_table,
return opp_table->clk_count > index;
}
/*
* Returns true if bandwidth table is large enough to contain the bandwidth index.
*/
static bool assert_bandwidth_index(struct opp_table *opp_table,
unsigned int index)
{
return opp_table->path_count > index;
}
/**
* dev_pm_opp_get_bw() - Gets the bandwidth corresponding to an opp
* @opp: opp for which bandwidth has to be returned for
@ -915,7 +924,8 @@ struct dev_pm_opp *dev_pm_opp_find_bw_ceil(struct device *dev, unsigned int *bw,
unsigned long temp = *bw;
struct dev_pm_opp *opp;
opp = _find_key_ceil(dev, &temp, index, true, _read_bw, NULL);
opp = _find_key_ceil(dev, &temp, index, true, _read_bw,
assert_bandwidth_index);
*bw = temp;
return opp;
}
@ -946,7 +956,8 @@ struct dev_pm_opp *dev_pm_opp_find_bw_floor(struct device *dev,
unsigned long temp = *bw;
struct dev_pm_opp *opp;
opp = _find_key_floor(dev, &temp, index, true, _read_bw, NULL);
opp = _find_key_floor(dev, &temp, index, true, _read_bw,
assert_bandwidth_index);
*bw = temp;
return opp;
}