On Wed, 2023-06-21 at 15:49 +0200, Alexandra Winter wrote: > From: Thorsten Winkler <twinkler@xxxxxxxxxxxxx> > > 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@xxxxxxxxxxxxx> > Signed-off-by: Thorsten Winkler <twinkler@xxxxxxxxxxxxx> > Signed-off-by: Alexandra Winter <wintera@xxxxxxxxxxxxx> > --- > drivers/s390/net/ctcm_dbug.c | 2 +- > drivers/s390/net/ctcm_main.c | 6 +++--- > drivers/s390/net/ctcm_main.h | 1 + > drivers/s390/net/ctcm_mpc.c | 18 ++++++++++-------- > drivers/s390/net/ctcm_sysfs.c | 36 +++++++++++++++++------------------ > 5 files changed, 33 insertions(+), 30 deletions(-) > > diff --git a/drivers/s390/net/ctcm_dbug.c b/drivers/s390/net/ctcm_dbug.c > index f7ec51db3cd6..b6f0e2f114b4 100644 > --- 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 e0fdd54bfeb7..79fac5314e67 100644 > --- a/drivers/s390/net/ctcm_main.c > +++ b/drivers/s390/net/ctcm_main.c > @@ -1340,7 +1340,7 @@ 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; > > /* > @@ -1505,8 +1505,8 @@ 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 90bd7b3f80c3..25164e8bf13d 100644 > --- 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 8ac213a55141..64996c86defc 100644 > --- 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 98680c2cc4e4..0c5d8a3eaa2e 100644 > --- 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); Not strictly related to this series, but it looks like there is opportunity for more cleanups? e.g. move legacy printk to pr_info(), etc... The series LGTM. Thanks, Paolo
