net: phy: fixed_phy: replace IDA with a bitmap

Size of array fmb_fixed_phys is small, so we can use a simple bitmap
instead of an IDA to manage dynamic allocation of fixed PHY's.
find_first_zero_bit() isn't atomic, so we need the loop to rule out
double allocation of a PHY address.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/d4614463-d532-41fc-92e9-ef97107aceb5@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/phy/fixed_phy.c b/drivers/net/phy/fixed_phy.c
index 7d6078d15709d61a49feaecb3e93c2822e6f176d..0b83fb30a5484d1f4571ce4da40f0112c63f9809 100644 (file)
--- a/drivers/net/phy/fixed_phy.c
+++ b/drivers/net/phy/fixed_phy.c
@@ -16,7 +16,6 @@
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/of.h>
-#include <linux/idr.h>
 #include <linux/netdevice.h>
 
 #include "swphy.h"
@@ -32,13 +31,13 @@ struct fixed_phy {
        int (*link_update)(struct net_device *, struct fixed_phy_status *);
 };
 
+static DECLARE_BITMAP(fixed_phy_ids, NUM_FP);
 static struct fixed_phy fmb_fixed_phys[NUM_FP];
 static struct mii_bus *fmb_mii_bus;
-static DEFINE_IDA(phy_fixed_ida);
 
 static struct fixed_phy *fixed_phy_find(int addr)
 {
-       return ida_exists(&phy_fixed_ida, addr) ? fmb_fixed_phys + addr : NULL;
+       return test_bit(addr, fixed_phy_ids) ? fmb_fixed_phys + addr : NULL;
 }
 
 int fixed_phy_change_carrier(struct net_device *dev, bool new_carrier)
@@ -113,7 +112,20 @@ static void fixed_phy_del(int phy_addr)
                return;
 
        memset(fp, 0, sizeof(*fp));
-       ida_free(&phy_fixed_ida, phy_addr);
+       clear_bit(phy_addr, fixed_phy_ids);
+}
+
+static int fixed_phy_get_free_addr(void)
+{
+       int addr;
+
+       do {
+               addr = find_first_zero_bit(fixed_phy_ids, NUM_FP);
+               if (addr == NUM_FP)
+                       return -ENOSPC;
+       } while (test_and_set_bit(addr, fixed_phy_ids));
+
+       return addr;
 }
 
 struct phy_device *fixed_phy_register(const struct fixed_phy_status *status,
@@ -131,7 +143,7 @@ struct phy_device *fixed_phy_register(const struct fixed_phy_status *status,
                return ERR_PTR(-EPROBE_DEFER);
 
        /* Get the next available PHY address, up to NUM_FP */
-       phy_addr = ida_alloc_max(&phy_fixed_ida, NUM_FP - 1, GFP_KERNEL);
+       phy_addr = fixed_phy_get_free_addr();
        if (phy_addr < 0)
                return ERR_PTR(phy_addr);
 
@@ -210,8 +222,6 @@ static void __exit fixed_mdio_bus_exit(void)
 {
        mdiobus_unregister(fmb_mii_bus);
        mdiobus_free(fmb_mii_bus);
-
-       ida_destroy(&phy_fixed_ida);
 }
 module_exit(fixed_mdio_bus_exit);