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phy: ti: tusb1210: Resolve charger-det crash if charger psy is unregistered

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The power_supply frame-work is not really designed for there to be
long living in kernel references to power_supply devices.

Specifically unregistering a power_supply while some other code has
a reference to it triggers a WARN in power_supply_unregister():

	WARN_ON(atomic_dec_return(&psy->use_cnt));

Folllowed by the power_supply still getting removed and the
backing data freed anyway, leaving the tusb1210 charger-detect code
with a dangling reference, resulting in a crash the next time
tusb1210_get_online() is called.

Fix this by only holding the reference in tusb1210_get_online()
freeing it at the end of the function. Note this still leaves
a theoretical race window, but it avoids the issue when manually
rmmod-ing the charger chip driver during development.

Fixes: 48969a5623 ("phy: ti: tusb1210: Add charger detection")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20240406140821.18624-1-hdegoede@redhat.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Hans de Goede 2024-04-06 16:08:21 +02:00 committed by Vinod Koul
parent 025a6f7448
commit bf6e4ee5c4
1 changed files with 12 additions and 11 deletions
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23
drivers/phy/ti/phy-tusb1210.c
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@ -69,7 +69,6 @@ struct tusb1210 {
struct delayed_work chg_det_work;
struct notifier_block psy_nb;
struct power_supply *psy;
struct power_supply *charger;
#endif
};
@ -236,19 +235,24 @@ static const char * const tusb1210_chargers[] = {
static bool tusb1210_get_online(struct tusb1210 *tusb)
{
struct power_supply *charger = NULL;
union power_supply_propval val;
int i;
bool online = false;
int i, ret;
for (i = 0; i < ARRAY_SIZE(tusb1210_chargers) && !tusb->charger; i++)
tusb->charger = power_supply_get_by_name(tusb1210_chargers[i]);
for (i = 0; i < ARRAY_SIZE(tusb1210_chargers) && !charger; i++)
charger = power_supply_get_by_name(tusb1210_chargers[i]);
if (!tusb->charger)
if (!charger)
return false;
if (power_supply_get_property(tusb->charger, POWER_SUPPLY_PROP_ONLINE, &val))
return false;
ret = power_supply_get_property(charger, POWER_SUPPLY_PROP_ONLINE, &val);
if (ret == 0)
online = val.intval;
return val.intval;
power_supply_put(charger);
return online;
}
static void tusb1210_chg_det_work(struct work_struct *work)
@ -473,9 +477,6 @@ static void tusb1210_remove_charger_detect(struct tusb1210 *tusb)
cancel_delayed_work_sync(&tusb->chg_det_work);
power_supply_unregister(tusb->psy);
}
if (tusb->charger)
power_supply_put(tusb->charger);
}
#else
static void tusb1210_probe_charger_detect(struct tusb1210 *tusb) { }