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net: sfp: add mutex to prevent concurrent state checks 

sfp_check_state can potentially be called by both a threaded IRQ handler
and delayed work. If it is concurrently called, it could result in
incorrect state management. Add a st_mutex to protect the state - this
lock gets taken outside of code that checks and handle state changes, and
the existing sm_mutex nests inside of it.

Suggested-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Robert Hancock <hancock@sedsystems.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Robert Hancock 2019-06-07 10:42:36 -06:00 committed by David S. Miller
parent 257c255985
commit 2158e856f5
1 changed files with 5 additions and 1 deletions
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6
drivers/net/phy/sfp.c
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@ -188,10 +188,11 @@ struct sfp {
int gpio_irq[GPIO_MAX];
bool attached;
struct mutex st_mutex; /* Protects state */
unsigned int state;
struct delayed_work poll;
struct delayed_work timeout;
struct mutex sm_mutex;
struct mutex sm_mutex; /* Protects state machine */
unsigned char sm_mod_state;
unsigned char sm_dev_state;
unsigned short sm_state;
@ -1721,6 +1722,7 @@ static void sfp_check_state(struct sfp *sfp)
{
unsigned int state, i, changed;
mutex_lock(&sfp->st_mutex);
state = sfp_get_state(sfp);
changed = state ^ sfp->state;
changed &= SFP_F_PRESENT | SFP_F_LOS | SFP_F_TX_FAULT;
@ -1746,6 +1748,7 @@ static void sfp_check_state(struct sfp *sfp)
sfp_sm_event(sfp, state & SFP_F_LOS ?
SFP_E_LOS_HIGH : SFP_E_LOS_LOW);
rtnl_unlock();
mutex_unlock(&sfp->st_mutex);
}
static irqreturn_t sfp_irq(int irq, void *data)
@ -1776,6 +1779,7 @@ static struct sfp *sfp_alloc(struct device *dev)
sfp->dev = dev;
mutex_init(&sfp->sm_mutex);
mutex_init(&sfp->st_mutex);
INIT_DELAYED_WORK(&sfp->poll, sfp_poll);
INIT_DELAYED_WORK(&sfp->timeout, sfp_timeout);