net: sfp: change st_mutex locking

Change st_mutex's use within SFP such that it only protects the various
state members, as it was originally supposed to, and isn't held while
making various calls outside the driver.

Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
index e5cd36e3a421e9b441f14827bbd1bef1262a8f48..bf7dac9977e1b89cfae39825976bc9ac0a0ad68d 100644 (file)
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -242,10 +242,17 @@ struct sfp {
 
        bool need_poll;
 
+       /* Access rules:
+        * state_hw_drive: st_mutex held
+        * state_hw_mask: st_mutex held
+        * state_soft_mask: st_mutex held
+        * state: st_mutex held unless reading input bits
+        */
        struct mutex st_mutex;                  /* Protects state */
        unsigned int state_hw_mask;
        unsigned int state_soft_mask;
        unsigned int state;
+
        struct delayed_work poll;
        struct delayed_work timeout;
        struct mutex sm_mutex;                  /* Protects state machine */
@@ -692,7 +699,6 @@ static void sfp_soft_start_poll(struct sfp *sfp)
        const struct sfp_eeprom_id *id = &sfp->id;
        unsigned int mask = 0;
 
-       sfp->state_soft_mask = 0;
        if (id->ext.enhopts & SFP_ENHOPTS_SOFT_TX_DISABLE)
                mask |= SFP_F_TX_DISABLE;
        if (id->ext.enhopts & SFP_ENHOPTS_SOFT_TX_FAULT)
@@ -700,19 +706,26 @@ static void sfp_soft_start_poll(struct sfp *sfp)
        if (id->ext.enhopts & SFP_ENHOPTS_SOFT_RX_LOS)
                mask |= SFP_F_LOS;
 
+       mutex_lock(&sfp->st_mutex);
        // Poll the soft state for hardware pins we want to ignore
        sfp->state_soft_mask = ~sfp->state_hw_mask & mask;
 
        if (sfp->state_soft_mask & (SFP_F_LOS | SFP_F_TX_FAULT) &&
            !sfp->need_poll)
                mod_delayed_work(system_wq, &sfp->poll, poll_jiffies);
+       mutex_unlock(&sfp->st_mutex);
 }
 
 static void sfp_soft_stop_poll(struct sfp *sfp)
 {
+       mutex_lock(&sfp->st_mutex);
        sfp->state_soft_mask = 0;
+       mutex_unlock(&sfp->st_mutex);
 }
 
+/* sfp_get_state() - must be called with st_mutex held, or in the
+ * initialisation path.
+ */
 static unsigned int sfp_get_state(struct sfp *sfp)
 {
        unsigned int soft = sfp->state_soft_mask & (SFP_F_LOS | SFP_F_TX_FAULT);
@@ -725,6 +738,9 @@ static unsigned int sfp_get_state(struct sfp *sfp)
        return state;
 }
 
+/* sfp_set_state() - must be called with st_mutex held, or in the
+ * initialisation path.
+ */
 static void sfp_set_state(struct sfp *sfp, unsigned int state)
 {
        sfp->set_state(sfp, state);
@@ -736,8 +752,10 @@ static void sfp_set_state(struct sfp *sfp, unsigned int state)
 
 static void sfp_mod_state(struct sfp *sfp, unsigned int mask, unsigned int set)
 {
+       mutex_lock(&sfp->st_mutex);
        sfp->state = (sfp->state & ~mask) | set;
        sfp_set_state(sfp, sfp->state);
+       mutex_unlock(&sfp->st_mutex);
 }
 
 static unsigned int sfp_check(void *buf, size_t len)
@@ -1603,16 +1621,18 @@ static void sfp_debugfs_exit(struct sfp *sfp)
 
 static void sfp_module_tx_fault_reset(struct sfp *sfp)
 {
-       unsigned int state = sfp->state;
-
-       if (state & SFP_F_TX_DISABLE)
-               return;
+       unsigned int state;
 
-       sfp_set_state(sfp, state | SFP_F_TX_DISABLE);
+       mutex_lock(&sfp->st_mutex);
+       state = sfp->state;
+       if (!(state & SFP_F_TX_DISABLE)) {
+               sfp_set_state(sfp, state | SFP_F_TX_DISABLE);
 
-       udelay(T_RESET_US);
+               udelay(T_RESET_US);
 
-       sfp_set_state(sfp, state);
+               sfp_set_state(sfp, state);
+       }
+       mutex_unlock(&sfp->st_mutex);
 }
 
 /* SFP state machine */
@@ -1957,6 +1977,7 @@ static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
        /* SFP module inserted - read I2C data */
        struct sfp_eeprom_id id;
        bool cotsworks_sfbg;
+       unsigned int mask;
        bool cotsworks;
        u8 check;
        int ret;
@@ -2096,14 +2117,13 @@ static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
        if (ret < 0)
                return ret;
 
-       /* Initialise state bits to use from hardware */
-       sfp->state_hw_mask = SFP_F_PRESENT;
+       mask = SFP_F_PRESENT;
        if (sfp->gpio[GPIO_TX_DISABLE])
-               sfp->state_hw_mask |= SFP_F_TX_DISABLE;
+               mask |= SFP_F_TX_DISABLE;
        if (sfp->gpio[GPIO_TX_FAULT])
-               sfp->state_hw_mask |= SFP_F_TX_FAULT;
+               mask |= SFP_F_TX_FAULT;
        if (sfp->gpio[GPIO_LOS])
-               sfp->state_hw_mask |= SFP_F_LOS;
+               mask |= SFP_F_LOS;
 
        sfp->module_t_start_up = T_START_UP;
        sfp->module_t_wait = T_WAIT;
@@ -2121,8 +2141,14 @@ static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
                sfp->mdio_protocol = MDIO_I2C_NONE;
 
        sfp->quirk = sfp_lookup_quirk(&id);
+
+       mutex_lock(&sfp->st_mutex);
+       /* Initialise state bits to use from hardware */
+       sfp->state_hw_mask = mask;
+
        if (sfp->quirk && sfp->quirk->fixup)
                sfp->quirk->fixup(sfp);
+       mutex_unlock(&sfp->st_mutex);
 
        return 0;
 }
@@ -2619,6 +2645,7 @@ static void sfp_check_state(struct sfp *sfp)
 
        state |= sfp->state & (SFP_F_TX_DISABLE | SFP_F_RATE_SELECT);
        sfp->state = state;
+       mutex_unlock(&sfp->st_mutex);
 
        mutex_lock(&sfp->sm_mutex);
        if (changed & SFP_F_PRESENT)
@@ -2633,7 +2660,6 @@ static void sfp_check_state(struct sfp *sfp)
                __sfp_sm_event(sfp, state & SFP_F_LOS ?
                                    SFP_E_LOS_HIGH : SFP_E_LOS_LOW);
        mutex_unlock(&sfp->sm_mutex);
-       mutex_unlock(&sfp->st_mutex);
        rtnl_unlock();
 }
 
@@ -2652,6 +2678,8 @@ static void sfp_poll(struct work_struct *work)
 
        sfp_check_state(sfp);
 
+       // st_mutex doesn't need to be held here for state_soft_mask,
+       // it's unimportant if we race while reading this.
        if (sfp->state_soft_mask & (SFP_F_LOS | SFP_F_TX_FAULT) ||
            sfp->need_poll)
                mod_delayed_work(system_wq, &sfp->poll, poll_jiffies);