airo: work around stack usage warning

gcc-11 with KASAN on 32-bit arm produces a warning about a function
that needs a lot of stack space:

drivers/net/wireless/cisco/airo.c: In function 'setup_card.constprop':
drivers/net/wireless/cisco/airo.c:3960:1: error: the frame size of 1512 bytes is larger than 1400 bytes [-Werror=frame-larger-than=]

Most of this is from a single large structure that could be dynamically
allocated or moved into the per-device structure.  However, as the callers
all seem to have a fairly well bounded call chain, the easiest change
is to pull out the part of the function that needs the large variables
into a separate function and mark that as noinline_for_stack. This does
not reduce the total stack usage, but it gets rid of the warning and
requires minimal changes otherwise.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210323131634.2669455-1-arnd@kernel.org

diff --git a/drivers/net/wireless/cisco/airo.c b/drivers/net/wireless/cisco/airo.c
index 60db38c..fd37d4d 100644 (file)
--- a/drivers/net/wireless/cisco/airo.c
+++ b/drivers/net/wireless/cisco/airo.c
@@ -3817,6 +3817,68 @@ static inline void set_auth_type(struct airo_info *local, int auth_type)
                local->last_auth = auth_type;
 }
 
+static int noinline_for_stack airo_readconfig(struct airo_info *ai, u8 *mac, int lock)
+{
+       int i, status;
+       /* large variables, so don't inline this function,
+        * maybe change to kmalloc
+        */
+       tdsRssiRid rssi_rid;
+       CapabilityRid cap_rid;
+
+       kfree(ai->SSID);
+       ai->SSID = NULL;
+       // general configuration (read/modify/write)
+       status = readConfigRid(ai, lock);
+       if (status != SUCCESS) return ERROR;
+
+       status = readCapabilityRid(ai, &cap_rid, lock);
+       if (status != SUCCESS) return ERROR;
+
+       status = PC4500_readrid(ai, RID_RSSI, &rssi_rid, sizeof(rssi_rid), lock);
+       if (status == SUCCESS) {
+               if (ai->rssi || (ai->rssi = kmalloc(512, GFP_KERNEL)) != NULL)
+                       memcpy(ai->rssi, (u8*)&rssi_rid + 2, 512); /* Skip RID length member */
+       }
+       else {
+               kfree(ai->rssi);
+               ai->rssi = NULL;
+               if (cap_rid.softCap & cpu_to_le16(8))
+                       ai->config.rmode |= RXMODE_NORMALIZED_RSSI;
+               else
+                       airo_print_warn(ai->dev->name, "unknown received signal "
+                                       "level scale");
+       }
+       ai->config.opmode = adhoc ? MODE_STA_IBSS : MODE_STA_ESS;
+       set_auth_type(ai, AUTH_OPEN);
+       ai->config.modulation = MOD_CCK;
+
+       if (le16_to_cpu(cap_rid.len) >= sizeof(cap_rid) &&
+           (cap_rid.extSoftCap & cpu_to_le16(1)) &&
+           micsetup(ai) == SUCCESS) {
+               ai->config.opmode |= MODE_MIC;
+               set_bit(FLAG_MIC_CAPABLE, &ai->flags);
+       }
+
+       /* Save off the MAC */
+       for (i = 0; i < ETH_ALEN; i++) {
+               mac[i] = ai->config.macAddr[i];
+       }
+
+       /* Check to see if there are any insmod configured
+          rates to add */
+       if (rates[0]) {
+               memset(ai->config.rates, 0, sizeof(ai->config.rates));
+               for (i = 0; i < 8 && rates[i]; i++) {
+                       ai->config.rates[i] = rates[i];
+               }
+       }
+       set_bit (FLAG_COMMIT, &ai->flags);
+
+       return SUCCESS;
+}
+
+
 static u16 setup_card(struct airo_info *ai, u8 *mac, int lock)
 {
        Cmd cmd;
@@ -3863,58 +3925,9 @@ static u16 setup_card(struct airo_info *ai, u8 *mac, int lock)
        if (lock)
                up(&ai->sem);
        if (ai->config.len == 0) {
-               int i;
-               tdsRssiRid rssi_rid;
-               CapabilityRid cap_rid;
-
-               kfree(ai->SSID);
-               ai->SSID = NULL;
-               // general configuration (read/modify/write)
-               status = readConfigRid(ai, lock);
-               if (status != SUCCESS) return ERROR;
-
-               status = readCapabilityRid(ai, &cap_rid, lock);
-               if (status != SUCCESS) return ERROR;
-
-               status = PC4500_readrid(ai, RID_RSSI,&rssi_rid, sizeof(rssi_rid), lock);
-               if (status == SUCCESS) {
-                       if (ai->rssi || (ai->rssi = kmalloc(512, GFP_KERNEL)) != NULL)
-                               memcpy(ai->rssi, (u8*)&rssi_rid + 2, 512); /* Skip RID length member */
-               }
-               else {
-                       kfree(ai->rssi);
-                       ai->rssi = NULL;
-                       if (cap_rid.softCap & cpu_to_le16(8))
-                               ai->config.rmode |= RXMODE_NORMALIZED_RSSI;
-                       else
-                               airo_print_warn(ai->dev->name, "unknown received signal "
-                                               "level scale");
-               }
-               ai->config.opmode = adhoc ? MODE_STA_IBSS : MODE_STA_ESS;
-               set_auth_type(ai, AUTH_OPEN);
-               ai->config.modulation = MOD_CCK;
-
-               if (le16_to_cpu(cap_rid.len) >= sizeof(cap_rid) &&
-                   (cap_rid.extSoftCap & cpu_to_le16(1)) &&
-                   micsetup(ai) == SUCCESS) {
-                       ai->config.opmode |= MODE_MIC;
-                       set_bit(FLAG_MIC_CAPABLE, &ai->flags);
-               }
-
-               /* Save off the MAC */
-               for (i = 0; i < ETH_ALEN; i++) {
-                       mac[i] = ai->config.macAddr[i];
-               }
-
-               /* Check to see if there are any insmod configured
-                  rates to add */
-               if (rates[0]) {
-                       memset(ai->config.rates, 0, sizeof(ai->config.rates));
-                       for (i = 0; i < 8 && rates[i]; i++) {
-                               ai->config.rates[i] = rates[i];
-                       }
-               }
-               set_bit (FLAG_COMMIT, &ai->flags);
+               status = airo_readconfig(ai, mac, lock);
+               if (status != SUCCESS)
+                       return ERROR;
        }
 
        /* Setup the SSIDs if present */