s390/ctcm: Convert sprintf/snprintf to scnprintf

This LWN article explains the why scnprintf is preferred over snprintf
in general
https://lwn.net/Articles/69419/
Ie. snprintf() returns what *would* be the resulting length, while
scnprintf() returns the actual length.

Note that ctcm_print_statistics() writes the data into the kernel log
and is therefore not suitable for sysfs_emit(). Observable behavior is
not changed, as there may be dependencies.

Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Thorsten Winkler <twinkler@linux.ibm.com>
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/drivers/s390/net/ctcm_dbug.c b/drivers/s390/net/ctcm_dbug.c
index f7ec51d..b6f0e2f 100644 (file)
--- a/drivers/s390/net/ctcm_dbug.c
+++ b/drivers/s390/net/ctcm_dbug.c
@@ -70,7 +70,7 @@ void ctcm_dbf_longtext(enum ctcm_dbf_names dbf_nix, int level, char *fmt, ...)
        if (!debug_level_enabled(ctcm_dbf[dbf_nix].id, level))
                return;
        va_start(args, fmt);
-       vsnprintf(dbf_txt_buf, sizeof(dbf_txt_buf), fmt, args);
+       vscnprintf(dbf_txt_buf, sizeof(dbf_txt_buf), fmt, args);
        va_end(args);
 
        debug_text_event(ctcm_dbf[dbf_nix].id, level, dbf_txt_buf);

diff --git a/drivers/s390/net/ctcm_main.c b/drivers/s390/net/ctcm_main.c
index 28db69d..6faf271 100644 (file)
--- a/drivers/s390/net/ctcm_main.c
+++ b/drivers/s390/net/ctcm_main.c
@@ -1333,7 +1333,7 @@ static int add_channel(struct ccw_device *cdev, enum ctcm_channel_types type,
                                        goto nomem_return;
 
        ch->cdev = cdev;
-       snprintf(ch->id, CTCM_ID_SIZE, "ch-%s", dev_name(&cdev->dev));
+       scnprintf(ch->id, CTCM_ID_SIZE, "ch-%s", dev_name(&cdev->dev));
        ch->type = type;
 
        /*
@@ -1498,8 +1498,8 @@ static int ctcm_new_device(struct ccwgroup_device *cgdev)
 
        type = get_channel_type(&cdev0->id);
 
-       snprintf(read_id, CTCM_ID_SIZE, "ch-%s", dev_name(&cdev0->dev));
-       snprintf(write_id, CTCM_ID_SIZE, "ch-%s", dev_name(&cdev1->dev));
+       scnprintf(read_id, CTCM_ID_SIZE, "ch-%s", dev_name(&cdev0->dev));
+       scnprintf(write_id, CTCM_ID_SIZE, "ch-%s", dev_name(&cdev1->dev));
 
        ret = add_channel(cdev0, type, priv);
        if (ret) {

diff --git a/drivers/s390/net/ctcm_main.h b/drivers/s390/net/ctcm_main.h
index 90bd7b3..25164e8 100644 (file)
--- a/drivers/s390/net/ctcm_main.h
+++ b/drivers/s390/net/ctcm_main.h
@@ -100,6 +100,7 @@ enum ctcm_channel_types {
 #define CTCM_PROTO_MPC         4
 #define CTCM_PROTO_MAX         4
 
+#define CTCM_STATSIZE_LIMIT    64
 #define CTCM_BUFSIZE_LIMIT     65535
 #define CTCM_BUFSIZE_DEFAULT   32768
 #define MPC_BUFSIZE_DEFAULT    CTCM_BUFSIZE_LIMIT

diff --git a/drivers/s390/net/ctcm_mpc.c b/drivers/s390/net/ctcm_mpc.c
index b8a226c..c44ba88 100644 (file)
--- a/drivers/s390/net/ctcm_mpc.c
+++ b/drivers/s390/net/ctcm_mpc.c
@@ -144,9 +144,9 @@ void ctcmpc_dumpit(char *buf, int len)
 
        for (ct = 0; ct < len; ct++, ptr++, rptr++) {
                if (sw == 0) {
-                       sprintf(addr, "%16.16llx", (__u64)rptr);
+                       scnprintf(addr, sizeof(addr), "%16.16llx", (__u64)rptr);
 
-                       sprintf(boff, "%4.4X", (__u32)ct);
+                       scnprintf(boff, sizeof(boff), "%4.4X", (__u32)ct);
                        bhex[0] = '\0';
                        basc[0] = '\0';
                }
@@ -155,7 +155,7 @@ void ctcmpc_dumpit(char *buf, int len)
                if (sw == 8)
                        strcat(bhex, "  ");
 
-               sprintf(tbuf, "%2.2llX", (__u64)*ptr);
+               scnprintf(tbuf, sizeof(tbuf), "%2.2llX", (__u64)*ptr);
 
                tbuf[2] = '\0';
                strcat(bhex, tbuf);
@@ -171,8 +171,8 @@ void ctcmpc_dumpit(char *buf, int len)
                        continue;
                if ((strcmp(duphex, bhex)) != 0) {
                        if (dup != 0) {
-                               sprintf(tdup,
-                                       "Duplicate as above to %s", addr);
+                               scnprintf(tdup, sizeof(tdup),
+                                         "Duplicate as above to %s", addr);
                                ctcm_pr_debug("                --- %s ---\n",
                                                tdup);
                        }
@@ -197,14 +197,16 @@ void ctcmpc_dumpit(char *buf, int len)
                        strcat(basc, " ");
                }
                if (dup != 0) {
-                       sprintf(tdup, "Duplicate as above to %s", addr);
+                       scnprintf(tdup, sizeof(tdup),
+                                 "Duplicate as above to %s", addr);
                        ctcm_pr_debug("                --- %s ---\n", tdup);
                }
                ctcm_pr_debug("   %s (+%s) : %s  [%s]\n",
                                        addr, boff, bhex, basc);
        } else {
                if (dup >= 1) {
-                       sprintf(tdup, "Duplicate as above to %s", addr);
+                       scnprintf(tdup, sizeof(tdup),
+                                 "Duplicate as above to %s", addr);
                        ctcm_pr_debug("                --- %s ---\n", tdup);
                }
                if (dup != 0) {
@@ -291,7 +293,7 @@ static struct net_device *ctcmpc_get_dev(int port_num)
        struct net_device *dev;
        struct ctcm_priv *priv;
 
-       sprintf(device, "%s%i", MPC_DEVICE_NAME, port_num);
+       scnprintf(device, sizeof(device), "%s%i", MPC_DEVICE_NAME, port_num);
 
        dev = __dev_get_by_name(&init_net, device);
 

diff --git a/drivers/s390/net/ctcm_sysfs.c b/drivers/s390/net/ctcm_sysfs.c
index 98680c2..0c5d8a3 100644 (file)
--- a/drivers/s390/net/ctcm_sysfs.c
+++ b/drivers/s390/net/ctcm_sysfs.c
@@ -86,24 +86,24 @@ static void ctcm_print_statistics(struct ctcm_priv *priv)
                return;
        p = sbuf;
 
-       p += sprintf(p, "  Device FSM state: %s\n",
-                    fsm_getstate_str(priv->fsm));
-       p += sprintf(p, "  RX channel FSM state: %s\n",
-                    fsm_getstate_str(priv->channel[CTCM_READ]->fsm));
-       p += sprintf(p, "  TX channel FSM state: %s\n",
-                    fsm_getstate_str(priv->channel[CTCM_WRITE]->fsm));
-       p += sprintf(p, "  Max. TX buffer used: %ld\n",
-                    priv->channel[WRITE]->prof.maxmulti);
-       p += sprintf(p, "  Max. chained SKBs: %ld\n",
-                    priv->channel[WRITE]->prof.maxcqueue);
-       p += sprintf(p, "  TX single write ops: %ld\n",
-                    priv->channel[WRITE]->prof.doios_single);
-       p += sprintf(p, "  TX multi write ops: %ld\n",
-                    priv->channel[WRITE]->prof.doios_multi);
-       p += sprintf(p, "  Netto bytes written: %ld\n",
-                    priv->channel[WRITE]->prof.txlen);
-       p += sprintf(p, "  Max. TX IO-time: %u\n",
-                    jiffies_to_usecs(priv->channel[WRITE]->prof.tx_time));
+       p += scnprintf(p, CTCM_STATSIZE_LIMIT, "  Device FSM state: %s\n",
+                      fsm_getstate_str(priv->fsm));
+       p += scnprintf(p, CTCM_STATSIZE_LIMIT, "  RX channel FSM state: %s\n",
+                      fsm_getstate_str(priv->channel[CTCM_READ]->fsm));
+       p += scnprintf(p, CTCM_STATSIZE_LIMIT, "  TX channel FSM state: %s\n",
+                      fsm_getstate_str(priv->channel[CTCM_WRITE]->fsm));
+       p += scnprintf(p, CTCM_STATSIZE_LIMIT, "  Max. TX buffer used: %ld\n",
+                      priv->channel[WRITE]->prof.maxmulti);
+       p += scnprintf(p, CTCM_STATSIZE_LIMIT, "  Max. chained SKBs: %ld\n",
+                      priv->channel[WRITE]->prof.maxcqueue);
+       p += scnprintf(p, CTCM_STATSIZE_LIMIT, "  TX single write ops: %ld\n",
+                      priv->channel[WRITE]->prof.doios_single);
+       p += scnprintf(p, CTCM_STATSIZE_LIMIT, "  TX multi write ops: %ld\n",
+                      priv->channel[WRITE]->prof.doios_multi);
+       p += scnprintf(p, CTCM_STATSIZE_LIMIT, "  Netto bytes written: %ld\n",
+                      priv->channel[WRITE]->prof.txlen);
+       p += scnprintf(p, CTCM_STATSIZE_LIMIT, "  Max. TX IO-time: %u\n",
+                      jiffies_to_usecs(priv->channel[WRITE]->prof.tx_time));
 
        printk(KERN_INFO "Statistics for %s:\n%s",
                                priv->channel[CTCM_WRITE]->netdev->name, sbuf);