[PATCH 3.16 250/305] net: phy: Manage fixed PHY address space using IDA

[Ben Hutchings]

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Florian Fainelli <f.faine...@gmail.com>

commit 69fc58a57e56bf5e39b48809aefffdaa1b04c945 upstream.

If we have a system which uses fixed PHY devices and calls
fixed_phy_register() then fixed_phy_unregister() we can exhaust the
number of fixed PHYs available after a while, since we keep incrementing
the variable phy_fixed_addr, but we never decrement it.

This patch fixes that by converting the fixed PHY allocation to using
IDA, which takes care of the allocation/dealloaction of the PHY
addresses for us.

Fixes: a75951217472 ("net: phy: extend fixed driver with fixed_phy_register()")
Signed-off-by: Florian Fainelli <f.faine...@gmail.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
[bwh: Backported to 3.16:
 - Adjust filename, context
 - fixed_phy_register() returns an integer, not a pointer/error]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 drivers/net/phy/fixed.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

--- a/drivers/net/phy/fixed.c
+++ b/drivers/net/phy/fixed.c
@@ -22,6 +22,7 @@
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/of.h>
+#include <linux/idr.h>
 
 #define MII_REGS_NUM 29
 
@@ -204,6 +205,8 @@ err_regs:
 }
 EXPORT_SYMBOL_GPL(fixed_phy_add);
 
+static DEFINE_IDA(phy_fixed_ida);
+
 void fixed_phy_del(int phy_addr)
 {
        struct fixed_mdio_bus *fmb = &platform_fmb;
@@ -213,15 +216,13 @@ void fixed_phy_del(int phy_addr)
                if (fp->addr == phy_addr) {
                        list_del(&fp->node);
                        kfree(fp);
+                       ida_simple_remove(&phy_fixed_ida, phy_addr);
                        return;
                }
        }
 }
 EXPORT_SYMBOL_GPL(fixed_phy_del);
 
-static int phy_fixed_addr;
-static DEFINE_SPINLOCK(phy_fixed_addr_lock);
-
 int fixed_phy_register(unsigned int irq,
                       struct fixed_phy_status *status,
                       struct device_node *np)
@@ -232,17 +233,15 @@ int fixed_phy_register(unsigned int irq,
        int ret;
 
        /* Get the next available PHY address, up to PHY_MAX_ADDR */
-       spin_lock(&phy_fixed_addr_lock);
-       if (phy_fixed_addr == PHY_MAX_ADDR) {
-               spin_unlock(&phy_fixed_addr_lock);
-               return -ENOSPC;
-       }
-       phy_addr = phy_fixed_addr++;
-       spin_unlock(&phy_fixed_addr_lock);
+       phy_addr = ida_simple_get(&phy_fixed_ida, 0, PHY_MAX_ADDR, GFP_KERNEL);
+       if (phy_addr < 0)
+               return phy_addr;
 
        ret = fixed_phy_add(irq, phy_addr, status);
-       if (ret < 0)
+       if (ret < 0) {
+               ida_simple_remove(&phy_fixed_ida, phy_addr);
                return ret;
+       }
 
        phy = get_phy_device(fmb->mii_bus, phy_addr, false);
        if (!phy || IS_ERR(phy)) {
@@ -317,6 +316,7 @@ static void __exit fixed_mdio_bus_exit(v
                list_del(&fp->node);
                kfree(fp);
        }
+       ida_destroy(&phy_fixed_ida);
 }
 module_exit(fixed_mdio_bus_exit);