The timestamps for the cache are all in boottime seconds, so they don't overflow 32-bit values, but the use of time_t is deprecated because it generally does overflow when used with wall-clock time.
There are multiple possible ways of avoiding it:
- leave time_t, which is safe here, but forces others to look into this code to determine that it is over and over.
- use a more generic type, like 'int' or 'long', which is known to be sufficient here but loses the documentation of referring to timestamps
- use ktime_t everywhere, and convert into seconds in the few places where we want realtime-seconds. The conversion is sometimes expensive, but not more so than the conversion we do today.
- use time64_t to clarify that this code is safe. Nothing would change for 64-bit architectures, but it is slightly less efficient on 32-bit architectures.
Without a clear winner of the three approaches above, this picks the last one, favouring readability over a small performance loss on 32-bit architectures.
Signed-off-by: Arnd Bergmann arnd@arndb.de --- include/linux/sunrpc/cache.h | 42 +++++++++++++++++-------------- net/sunrpc/auth_gss/svcauth_gss.c | 2 +- net/sunrpc/cache.c | 18 ++++++------- net/sunrpc/svcauth_unix.c | 10 ++++---- 4 files changed, 38 insertions(+), 34 deletions(-)
diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h index f8603724fbee..fa46de3a8f2b 100644 --- a/include/linux/sunrpc/cache.h +++ b/include/linux/sunrpc/cache.h @@ -45,8 +45,8 @@ */ struct cache_head { struct hlist_node cache_list; - time_t expiry_time; /* After time time, don't use the data */ - time_t last_refresh; /* If CACHE_PENDING, this is when upcall was + time64_t expiry_time; /* After time time, don't use the data */ + time64_t last_refresh; /* If CACHE_PENDING, this is when upcall was * sent, else this is when update was * received, though it is alway set to * be *after* ->flush_time. @@ -95,22 +95,22 @@ struct cache_detail { /* fields below this comment are for internal use * and should not be touched by cache owners */ - time_t flush_time; /* flush all cache items with + time64_t flush_time; /* flush all cache items with * last_refresh at or earlier * than this. last_refresh * is never set at or earlier * than this. */ struct list_head others; - time_t nextcheck; + time64_t nextcheck; int entries;
/* fields for communication over channel */ struct list_head queue;
atomic_t writers; /* how many time is /channel open */ - time_t last_close; /* if no writers, when did last close */ - time_t last_warn; /* when we last warned about no writers */ + time64_t last_close; /* if no writers, when did last close */ + time64_t last_warn; /* when we last warned about no writers */
union { struct proc_dir_entry *procfs; @@ -147,18 +147,22 @@ struct cache_deferred_req { * timestamps kept in the cache are expressed in seconds * since boot. This is the best for measuring differences in * real time. + * This reimplemnts ktime_get_boottime_seconds() in a slightly + * faster but less accurate way. When we end up converting + * back to wallclock (CLOCK_REALTIME), that error often + * cancels out during the reverse operation. */ -static inline time_t seconds_since_boot(void) +static inline time64_t seconds_since_boot(void) { - struct timespec boot; - getboottime(&boot); - return get_seconds() - boot.tv_sec; + struct timespec64 boot; + getboottime64(&boot); + return ktime_get_seconds() - boot.tv_sec; }
-static inline time_t convert_to_wallclock(time_t sinceboot) +static inline time64_t convert_to_wallclock(time64_t sinceboot) { - struct timespec boot; - getboottime(&boot); + struct timespec64 boot; + getboottime64(&boot); return boot.tv_sec + sinceboot; }
@@ -273,7 +277,7 @@ static inline int get_uint(char **bpp, unsigned int *anint) return 0; }
-static inline int get_time(char **bpp, time_t *time) +static inline int get_time(char **bpp, time64_t *time) { char buf[50]; long long ll; @@ -287,20 +291,20 @@ static inline int get_time(char **bpp, time_t *time) if (kstrtoll(buf, 0, &ll)) return -EINVAL;
- *time = (time_t)ll; + *time = ll; return 0; }
-static inline time_t get_expiry(char **bpp) +static inline time64_t get_expiry(char **bpp) { - time_t rv; - struct timespec boot; + time64_t rv; + struct timespec64 boot;
if (get_time(bpp, &rv)) return 0; if (rv < 0) return 0; - getboottime(&boot); + getboottime64(&boot); return rv - boot.tv_sec; }
diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c index 30ed5585a42a..6268a2c7229d 100644 --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -200,7 +200,7 @@ static int rsi_parse(struct cache_detail *cd, char *ep; int len; struct rsi rsii, *rsip = NULL; - time_t expiry; + time64_t expiry; int status = -EINVAL;
memset(&rsii, 0, sizeof(rsii)); diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index a349094f6fb7..18d73d1f6734 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -42,7 +42,7 @@ static bool cache_listeners_exist(struct cache_detail *detail);
static void cache_init(struct cache_head *h, struct cache_detail *detail) { - time_t now = seconds_since_boot(); + time64_t now = seconds_since_boot(); INIT_HLIST_NODE(&h->cache_list); h->flags = 0; kref_init(&h->ref); @@ -54,7 +54,7 @@ static void cache_init(struct cache_head *h, struct cache_detail *detail) }
static inline int cache_is_valid(struct cache_head *h); -static void cache_fresh_locked(struct cache_head *head, time_t expiry, +static void cache_fresh_locked(struct cache_head *head, time64_t expiry, struct cache_detail *detail); static void cache_fresh_unlocked(struct cache_head *head, struct cache_detail *detail); @@ -145,10 +145,10 @@ EXPORT_SYMBOL_GPL(sunrpc_cache_lookup_rcu);
static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch);
-static void cache_fresh_locked(struct cache_head *head, time_t expiry, +static void cache_fresh_locked(struct cache_head *head, time64_t expiry, struct cache_detail *detail) { - time_t now = seconds_since_boot(); + time64_t now = seconds_since_boot(); if (now <= detail->flush_time) /* ensure it isn't immediately treated as expired */ now = detail->flush_time + 1; @@ -280,7 +280,7 @@ int cache_check(struct cache_detail *detail, struct cache_head *h, struct cache_req *rqstp) { int rv; - long refresh_age, age; + time64_t refresh_age, age;
/* First decide return status as best we can */ rv = cache_is_valid(h); @@ -294,7 +294,7 @@ int cache_check(struct cache_detail *detail, rv = -ENOENT; } else if (rv == -EAGAIN || (h->expiry_time != 0 && age > refresh_age/2)) { - dprintk("RPC: Want update, refage=%ld, age=%ld\n", + dprintk("RPC: Want update, refage=%lld, age=%lld\n", refresh_age, age); if (!test_and_set_bit(CACHE_PENDING, &h->flags)) { switch (cache_make_upcall(detail, h)) { @@ -1410,7 +1410,7 @@ static int c_show(struct seq_file *m, void *p) return cd->cache_show(m, cd, NULL);
ifdebug(CACHE) - seq_printf(m, "# expiry=%ld refcnt=%d flags=%lx\n", + seq_printf(m, "# expiry=%lld refcnt=%d flags=%lx\n", convert_to_wallclock(cp->expiry_time), kref_read(&cp->ref), cp->flags); cache_get(cp); @@ -1483,7 +1483,7 @@ static ssize_t read_flush(struct file *file, char __user *buf, char tbuf[22]; size_t len;
- len = snprintf(tbuf, sizeof(tbuf), "%lu\n", + len = snprintf(tbuf, sizeof(tbuf), "%llu\n", convert_to_wallclock(cd->flush_time)); return simple_read_from_buffer(buf, count, ppos, tbuf, len); } @@ -1494,7 +1494,7 @@ static ssize_t write_flush(struct file *file, const char __user *buf, { char tbuf[20]; char *ep; - time_t now; + time64_t now;
if (*ppos || count > sizeof(tbuf)-1) return -EINVAL; diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c index 5c04ba7d456b..04aa80a2d752 100644 --- a/net/sunrpc/svcauth_unix.c +++ b/net/sunrpc/svcauth_unix.c @@ -166,7 +166,7 @@ static void ip_map_request(struct cache_detail *cd, }
static struct ip_map *__ip_map_lookup(struct cache_detail *cd, char *class, struct in6_addr *addr); -static int __ip_map_update(struct cache_detail *cd, struct ip_map *ipm, struct unix_domain *udom, time_t expiry); +static int __ip_map_update(struct cache_detail *cd, struct ip_map *ipm, struct unix_domain *udom, time64_t expiry);
static int ip_map_parse(struct cache_detail *cd, char *mesg, int mlen) @@ -187,7 +187,7 @@ static int ip_map_parse(struct cache_detail *cd,
struct ip_map *ipmp; struct auth_domain *dom; - time_t expiry; + time64_t expiry;
if (mesg[mlen-1] != '\n') return -EINVAL; @@ -308,7 +308,7 @@ static inline struct ip_map *ip_map_lookup(struct net *net, char *class, }
static int __ip_map_update(struct cache_detail *cd, struct ip_map *ipm, - struct unix_domain *udom, time_t expiry) + struct unix_domain *udom, time64_t expiry) { struct ip_map ip; struct cache_head *ch; @@ -328,7 +328,7 @@ static int __ip_map_update(struct cache_detail *cd, struct ip_map *ipm, }
static inline int ip_map_update(struct net *net, struct ip_map *ipm, - struct unix_domain *udom, time_t expiry) + struct unix_domain *udom, time64_t expiry) { struct sunrpc_net *sn;
@@ -491,7 +491,7 @@ static int unix_gid_parse(struct cache_detail *cd, int rv; int i; int err; - time_t expiry; + time64_t expiry; struct unix_gid ug, *ugp;
if (mesg[mlen - 1] != '\n')