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s390/ctcm: Convert sprintf/snprintf to scnprintf
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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>
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Thorsten Winkler authored and Paolo Abeni committed Jun 23, 2023
1 parent d585e4b commit 1471d85
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Showing 5 changed files with 33 additions and 30 deletions.
2 changes: 1 addition & 1 deletion drivers/s390/net/ctcm_dbug.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
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6 changes: 3 additions & 3 deletions drivers/s390/net/ctcm_main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;

/*
Expand Down Expand Up @@ -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) {
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1 change: 1 addition & 0 deletions drivers/s390/net/ctcm_main.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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
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18 changes: 10 additions & 8 deletions drivers/s390/net/ctcm_mpc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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';
}
Expand All @@ -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);
Expand All @@ -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);
}
Expand All @@ -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) {
Expand Down Expand Up @@ -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);

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36 changes: 18 additions & 18 deletions drivers/s390/net/ctcm_sysfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down

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