| Message ID | 1412263501-6572-3-git-send-email-nicolas.dichtel@6wind.com |
|---|---|
| State | RFC, archived |
| Delegated to: | David Miller |
| Headers | show |
On Thu, 2 Oct 2014 17:25:01 +0200 Nicolas Dichtel <nicolas.dichtel@6wind.com> wrote: > From: Thierry Herbelot <thierry.herbelot@6wind.com> > > The current implementation for the directories in /proc is using a single > linked list. This is slow when handling directories with large numbers of > entries (eg netdevice-related entries when lots of tunnels are opened). > > This patch enables multiple linked lists. A hash based on the entry name is > used to select the linked list for one given entry. > > The speed creation of netdevices is faster as shorter linked lists must be > scanned when adding a new netdevice. > > Here are some numbers: > > dummy30000.batch contains 30 000 times 'link add type dummy'. > > Before the patch: > time ip -b dummy30000.batch > real 2m32.221s > user 0m0.380s > sys 2m30.610s > > After the patch: > time ip -b dummy30000.batch > real 1m57.190s > user 0m0.350s > sys 1m56.120s > > The single 'subdir' list head is replaced by a subdir hash table. The subdir > hash buckets are only allocated for directories. The number of hash buckets > is a compile-time parameter. > > For all functions which handle directory entries, an additional check on the > directory nature of the dir entry ensures that pde_hash_buckets was allocated. > This check was not needed as subdir was present for all dir entries, whether > actual directories or simple files. > > Signed-off-by: Thierry Herbelot <thierry.herbelot@6wind.com> > Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> I think the speed up is a good idea and makes sense. It would be better to use exist hlist macros for hash table rather than open coding it. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Oct 02, 2014 at 05:25:01PM +0200, Nicolas Dichtel wrote: > +static inline unsigned int proc_pde_name_hash(const unsigned char *name, > + const unsigned int len) > +{ > + return full_name_hash(name, len) & PROC_PDE_HASH_MASK; > +} PDE already stands for "proc dir entry" :^) Alexey -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Nicolas Dichtel <nicolas.dichtel@6wind.com> writes: > From: Thierry Herbelot <thierry.herbelot@6wind.com> > > The current implementation for the directories in /proc is using a single > linked list. This is slow when handling directories with large numbers of > entries (eg netdevice-related entries when lots of tunnels are opened). > > This patch enables multiple linked lists. A hash based on the entry name is > used to select the linked list for one given entry. > > The speed creation of netdevices is faster as shorter linked lists must be > scanned when adding a new netdevice. Is the directory of primary concern /proc/net/dev/snmp6 ? Unless I have configured my networking stack weird by mistake that is the only directory under /proc/net that grows when we add an interface. I just want to make certain I am seeing the same things that you are seeing. I feel silly for overlooking this directory when the rest of the scalability work was done. > Here are some numbers: > > dummy30000.batch contains 30 000 times 'link add type dummy'. > > Before the patch: > time ip -b dummy30000.batch > real 2m32.221s > user 0m0.380s > sys 2m30.610s > > After the patch: > time ip -b dummy30000.batch > real 1m57.190s > user 0m0.350s > sys 1m56.120s > > The single 'subdir' list head is replaced by a subdir hash table. The subdir > hash buckets are only allocated for directories. The number of hash buckets > is a compile-time parameter. That looks like a nice speed up. A couple of things. With sysfs and sysctl when faced this class of challenge we used an rbtree instead of a hash table. That should use less memory and scale better. I am concerned about a fixed sized hash table moving the location where we fall off a cliff but not removing the cliff itself. I suppose it would be possible to use the new fancy resizable hash tables but previous work on sysctl and sysfs suggests that we don't look up these entries sufficiently to require a hash table. We just need a data structure that doesn't fall over at scale, and the rbtrees seem to do that very nicely. > For all functions which handle directory entries, an additional check on the > directory nature of the dir entry ensures that pde_hash_buckets was allocated. > This check was not needed as subdir was present for all dir entries, whether > actual directories or simple files. That bit of logic seems reasonable. Eric -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Oct 02, 2014 at 11:01:50AM -0700, Eric W. Biederman wrote: > Nicolas Dichtel <nicolas.dichtel@6wind.com> writes: > > > From: Thierry Herbelot <thierry.herbelot@6wind.com> > > > > The current implementation for the directories in /proc is using a single > > linked list. This is slow when handling directories with large numbers of > > entries (eg netdevice-related entries when lots of tunnels are opened). > > > > This patch enables multiple linked lists. A hash based on the entry name is > > used to select the linked list for one given entry. > > > > The speed creation of netdevices is faster as shorter linked lists must be > > scanned when adding a new netdevice. > > Is the directory of primary concern /proc/net/dev/snmp6 ? > > Unless I have configured my networking stack weird by mistake that > is the only directory under /proc/net that grows when we add an > interface. > > I just want to make certain I am seeing the same things that you are > seeing. > > I feel silly for overlooking this directory when the rest of the > scalability work was done. Slowdown comes from "duplicate name" check: for (tmp = dir->subdir; tmp; tmp = tmp->next) if (strcmp(tmp->name, dp->name) == 0) { WARN(1, "proc_dir_entry '%s/%s' already registered\n", dir->name, dp->name); break; } Removal can be made O(1) after switching to doubly-linked list. Alexey -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Alexey Dobriyan <adobriyan@gmail.com> writes: > On Thu, Oct 02, 2014 at 11:01:50AM -0700, Eric W. Biederman wrote: >> Nicolas Dichtel <nicolas.dichtel@6wind.com> writes: >> >> > From: Thierry Herbelot <thierry.herbelot@6wind.com> >> > >> > The current implementation for the directories in /proc is using a single >> > linked list. This is slow when handling directories with large numbers of >> > entries (eg netdevice-related entries when lots of tunnels are opened). >> > >> > This patch enables multiple linked lists. A hash based on the entry name is >> > used to select the linked list for one given entry. >> > >> > The speed creation of netdevices is faster as shorter linked lists must be >> > scanned when adding a new netdevice. >> >> Is the directory of primary concern /proc/net/dev/snmp6 ? >> >> Unless I have configured my networking stack weird by mistake that >> is the only directory under /proc/net that grows when we add an >> interface. >> >> I just want to make certain I am seeing the same things that you are >> seeing. >> >> I feel silly for overlooking this directory when the rest of the >> scalability work was done. > > Slowdown comes from "duplicate name" check: > > for (tmp = dir->subdir; tmp; tmp = tmp->next) > if (strcmp(tmp->name, dp->name) == 0) { > WARN(1, "proc_dir_entry '%s/%s' already registered\n", > dir->name, dp->name); > break; > } > > Removal can be made O(1) after switching to doubly-linked list. Yes. There is the however unfortunate fact that proc directories exist to be used. If we don't switch to a better data structure than a linked list the actual use will then opening of the files under /proc/net/dev/snmp6/ will become O(N^2). Which doesn't help much (assuming those files are good for something). If those files aren't actually useful we should just make registering them a config option. Deprecate them strongly and let only people who need extreme backwards compatibility enable them. Alexey do you know that those files aren't useful? Unless we know otherwise we should make those files useful. Eric -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, 02 Oct 2014 14:07:37 -0700 ebiederm@xmission.com (Eric W. Biederman) wrote: > Alexey Dobriyan <adobriyan@gmail.com> writes: > > > On Thu, Oct 02, 2014 at 11:01:50AM -0700, Eric W. Biederman wrote: > >> Nicolas Dichtel <nicolas.dichtel@6wind.com> writes: > >> > >> > From: Thierry Herbelot <thierry.herbelot@6wind.com> > >> > > >> > The current implementation for the directories in /proc is using a single > >> > linked list. This is slow when handling directories with large numbers of > >> > entries (eg netdevice-related entries when lots of tunnels are opened). > >> > > >> > This patch enables multiple linked lists. A hash based on the entry name is > >> > used to select the linked list for one given entry. > >> > > >> > The speed creation of netdevices is faster as shorter linked lists must be > >> > scanned when adding a new netdevice. > >> > >> Is the directory of primary concern /proc/net/dev/snmp6 ? > >> > >> Unless I have configured my networking stack weird by mistake that > >> is the only directory under /proc/net that grows when we add an > >> interface. > >> > >> I just want to make certain I am seeing the same things that you are > >> seeing. > >> > >> I feel silly for overlooking this directory when the rest of the > >> scalability work was done. > > > > Slowdown comes from "duplicate name" check: > > > > for (tmp = dir->subdir; tmp; tmp = tmp->next) > > if (strcmp(tmp->name, dp->name) == 0) { > > WARN(1, "proc_dir_entry '%s/%s' already registered\n", > > dir->name, dp->name); > > break; > > } > > > > Removal can be made O(1) after switching to doubly-linked list. > > Yes. There is the however unfortunate fact that proc directories exist > to be used. If we don't switch to a better data structure than a linked > list the actual use will then opening of the files under > /proc/net/dev/snmp6/ will become O(N^2). Which doesn't help much > (assuming those files are good for something). > > If those files aren't actually useful we should just make registering > them a config option. Deprecate them strongly and let only people who > need extreme backwards compatibility enable them. Net-snmp uses them (agent/mibgroup/mibII/kernel_linux.c) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Le 02/10/2014 23:07, Eric W. Biederman a écrit : > Alexey Dobriyan <adobriyan@gmail.com> writes: > >> On Thu, Oct 02, 2014 at 11:01:50AM -0700, Eric W. Biederman wrote: >>> Nicolas Dichtel <nicolas.dichtel@6wind.com> writes: >>> >>>> From: Thierry Herbelot <thierry.herbelot@6wind.com> >>>> >>>> The current implementation for the directories in /proc is using a single >>>> linked list. This is slow when handling directories with large numbers of >>>> entries (eg netdevice-related entries when lots of tunnels are opened). >>>> >>>> This patch enables multiple linked lists. A hash based on the entry name is >>>> used to select the linked list for one given entry. >>>> >>>> The speed creation of netdevices is faster as shorter linked lists must be >>>> scanned when adding a new netdevice. >>> >>> Is the directory of primary concern /proc/net/dev/snmp6 ? >>> >>> Unless I have configured my networking stack weird by mistake that >>> is the only directory under /proc/net that grows when we add an >>> interface. >>> >>> I just want to make certain I am seeing the same things that you are >>> seeing. >>> >>> I feel silly for overlooking this directory when the rest of the >>> scalability work was done. >> >> Slowdown comes from "duplicate name" check: >> >> for (tmp = dir->subdir; tmp; tmp = tmp->next) >> if (strcmp(tmp->name, dp->name) == 0) { >> WARN(1, "proc_dir_entry '%s/%s' already registered\n", >> dir->name, dp->name); >> break; >> } >> >> Removal can be made O(1) after switching to doubly-linked list. > > Yes. There is the however unfortunate fact that proc directories exist > to be used. If we don't switch to a better data structure than a linked > list the actual use will then opening of the files under > /proc/net/dev/snmp6/ will become O(N^2). Which doesn't help much > (assuming those files are good for something). > > If those files aren't actually useful we should just make registering > them a config option. Deprecate them strongly and let only people who > need extreme backwards compatibility enable them. > > Alexey do you know that those files aren't useful? Unless we know > otherwise we should make those files useful. This was proposed and nacked in a first version: http://thread.gmane.org/gmane.linux.network/285840/ Regards, Nicolas -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Oct 2, 2014 at 6:25 PM, Nicolas Dichtel <nicolas.dichtel@6wind.com> wrote: > --- a/fs/proc/generic.c > +++ b/fs/proc/generic.c > @@ -81,10 +81,13 @@ static int __xlate_proc_name(const char *name, struct proc_dir_entry **ret, > + if (!S_ISDIR(de->mode)) > + return -EINVAL; There are way too many S_ISDIR checks. In lookup and readdir, it is guaranteed that PDE is directory. I'd say all of them aren't needed because non-directories have ->subdir = NULL and directories have ->subdir != NULL which transforms into hashtable or rbtree or whatever, so you only need to guarantee only directories appear where they are expected and fearlessly use your new data structure traversing directories. Alexey -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Le 02/10/2014 19:28, Alexey Dobriyan a écrit : > On Thu, Oct 02, 2014 at 05:25:01PM +0200, Nicolas Dichtel wrote: >> +static inline unsigned int proc_pde_name_hash(const unsigned char *name, >> + const unsigned int len) >> +{ >> + return full_name_hash(name, len) & PROC_PDE_HASH_MASK; >> +} > > PDE already stands for "proc dir entry" :^) > > Alexey > Oops, will fix it in v2. Thank you, Nicolas -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Le 03/10/2014 12:55, Alexey Dobriyan a écrit : > On Thu, Oct 2, 2014 at 6:25 PM, Nicolas Dichtel > <nicolas.dichtel@6wind.com> wrote: >> --- a/fs/proc/generic.c >> +++ b/fs/proc/generic.c >> @@ -81,10 +81,13 @@ static int __xlate_proc_name(const char *name, struct proc_dir_entry **ret, > >> + if (!S_ISDIR(de->mode)) >> + return -EINVAL; > > There are way too many S_ISDIR checks. > In lookup and readdir, it is guaranteed that PDE is directory. > > I'd say all of them aren't needed because non-directories have > ->subdir = NULL and > directories have ->subdir != NULL which transforms into hashtable or > rbtree or whatever, > so you only need to guarantee only directories appear where they are > expected and > fearlessly use your new data structure traversing directories. To be honest, they was put during the debug stage and I hesitated to remove them at the end. I will remove them! Thank you, Nicolas -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Le 02/10/2014 20:01, Eric W. Biederman a écrit : > Nicolas Dichtel <nicolas.dichtel@6wind.com> writes: > >> From: Thierry Herbelot <thierry.herbelot@6wind.com> >> >> The current implementation for the directories in /proc is using a single >> linked list. This is slow when handling directories with large numbers of >> entries (eg netdevice-related entries when lots of tunnels are opened). >> >> This patch enables multiple linked lists. A hash based on the entry name is >> used to select the linked list for one given entry. >> >> The speed creation of netdevices is faster as shorter linked lists must be >> scanned when adding a new netdevice. > > Is the directory of primary concern /proc/net/dev/snmp6 ? Yes. > > Unless I have configured my networking stack weird by mistake that > is the only directory under /proc/net that grows when we add an > interface. > > I just want to make certain I am seeing the same things that you are > seeing. > > I feel silly for overlooking this directory when the rest of the > scalability work was done. > >> Here are some numbers: >> >> dummy30000.batch contains 30 000 times 'link add type dummy'. >> >> Before the patch: >> time ip -b dummy30000.batch >> real 2m32.221s >> user 0m0.380s >> sys 2m30.610s >> >> After the patch: >> time ip -b dummy30000.batch >> real 1m57.190s >> user 0m0.350s >> sys 1m56.120s >> >> The single 'subdir' list head is replaced by a subdir hash table. The subdir >> hash buckets are only allocated for directories. The number of hash buckets >> is a compile-time parameter. > > That looks like a nice speed up. A couple of things. > > With sysfs and sysctl when faced this class of challenge we used an > rbtree instead of a hash table. That should use less memory and scale > better. > > I am concerned about a fixed sized hash table moving the location where > we fall off a cliff but not removing the cliff itself. > > I suppose it would be possible to use the new fancy resizable hash > tables but previous work on sysctl and sysfs suggests that we don't look > up these entries sufficiently to require a hash table. We just need a > data structure that doesn't fall over at scale, and the rbtrees seem to > do that very nicely. Ok, I will have a look at it. Thank you, Nicolas -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Le 02/10/2014 18:46, Stephen Hemminger a écrit : > On Thu, 2 Oct 2014 17:25:01 +0200 > Nicolas Dichtel <nicolas.dichtel@6wind.com> wrote: > >> From: Thierry Herbelot <thierry.herbelot@6wind.com> >> >> The current implementation for the directories in /proc is using a single >> linked list. This is slow when handling directories with large numbers of >> entries (eg netdevice-related entries when lots of tunnels are opened). >> >> This patch enables multiple linked lists. A hash based on the entry name is >> used to select the linked list for one given entry. >> >> The speed creation of netdevices is faster as shorter linked lists must be >> scanned when adding a new netdevice. >> >> Here are some numbers: >> >> dummy30000.batch contains 30 000 times 'link add type dummy'. >> >> Before the patch: >> time ip -b dummy30000.batch >> real 2m32.221s >> user 0m0.380s >> sys 2m30.610s >> >> After the patch: >> time ip -b dummy30000.batch >> real 1m57.190s >> user 0m0.350s >> sys 1m56.120s >> >> The single 'subdir' list head is replaced by a subdir hash table. The subdir >> hash buckets are only allocated for directories. The number of hash buckets >> is a compile-time parameter. >> >> For all functions which handle directory entries, an additional check on the >> directory nature of the dir entry ensures that pde_hash_buckets was allocated. >> This check was not needed as subdir was present for all dir entries, whether >> actual directories or simple files. >> >> Signed-off-by: Thierry Herbelot <thierry.herbelot@6wind.com> >> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> > > I think the speed up is a good idea and makes sense. > It would be better to use exist hlist macros for hash table rather than > open coding it. > Right, I will rework this after looking at rbtree. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
When a lot of netdevices are created, one of the bottleneck is the creation of proc entries. This serie aims to accelerate this part. I'm not sure against which tree this patch should be done. I've done it against linux.git. RFCv1 -> v2 - use a red-black tree instead of a hash list fs/proc/generic.c | 164 ++++++++++++++++++++++++++++++++++------------------- fs/proc/internal.h | 11 ++-- fs/proc/proc_net.c | 1 + fs/proc/root.c | 1 + 4 files changed, 113 insertions(+), 64 deletions(-) Comments are welcome. Regards, Nicolas -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 317b72641ebf..c3af8c289c7e 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -81,10 +81,13 @@ static int __xlate_proc_name(const char *name, struct proc_dir_entry **ret, const char *cp = name, *next; struct proc_dir_entry *de; unsigned int len; + unsigned int name_hash; de = *ret; if (!de) de = &proc_root; + if (!S_ISDIR(de->mode)) + return -EINVAL; while (1) { next = strchr(cp, '/'); @@ -92,7 +95,9 @@ static int __xlate_proc_name(const char *name, struct proc_dir_entry **ret, break; len = next - cp; - for (de = de->subdir; de ; de = de->next) { + name_hash = proc_pde_name_hash(cp, len); + for (de = de->pde_hash_buckets[name_hash]; de; + de = de->next) { if (proc_match(len, cp, de)) break; } @@ -180,10 +185,15 @@ static const struct inode_operations proc_link_inode_operations = { struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir, struct dentry *dentry) { + unsigned int name_hash; struct inode *inode; + if (!S_ISDIR(de->mode)) + return NULL; spin_lock(&proc_subdir_lock); - for (de = de->subdir; de ; de = de->next) { + name_hash = proc_pde_name_hash(dentry->d_name.name, + dentry->d_name.len); + for (de = de->pde_hash_buckets[name_hash]; de ; de = de->next) { if (de->namelen != dentry->d_name.len) continue; if (!memcmp(dentry->d_name.name, de->name, de->namelen)) { @@ -219,18 +229,30 @@ struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry, int proc_readdir_de(struct proc_dir_entry *de, struct file *file, struct dir_context *ctx) { + struct proc_dir_entry *dir; + unsigned int hash_idx = 0; int i; + dir = de; + if (!S_ISDIR(dir->mode)) + return -EINVAL; if (!dir_emit_dots(file, ctx)) return 0; spin_lock(&proc_subdir_lock); - de = de->subdir; + /* try first hash bucket */ + de = de->pde_hash_buckets[0]; + i = ctx->pos - 2; for (;;) { if (!de) { - spin_unlock(&proc_subdir_lock); - return 0; + /* try next hash bucket if one is availalable */ + hash_idx = find_next_hash_bucket(dir, hash_idx + 1); + if (hash_idx == PROC_PDE_HASH_BUCKETS) { + spin_unlock(&proc_subdir_lock); + return 0; + } + de = dir->pde_hash_buckets[hash_idx]; } if (!i) break; @@ -250,6 +272,12 @@ int proc_readdir_de(struct proc_dir_entry *de, struct file *file, spin_lock(&proc_subdir_lock); ctx->pos++; next = de->next; + if (!next) { + /* try next hash bucket if one is availalable */ + hash_idx = find_next_hash_bucket(dir, hash_idx + 1); + if (hash_idx != PROC_PDE_HASH_BUCKETS) + next = dir->pde_hash_buckets[hash_idx]; + } pde_put(de); de = next; } while (de); @@ -287,8 +315,12 @@ static const struct inode_operations proc_dir_inode_operations = { static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp) { struct proc_dir_entry *tmp; + unsigned int name_hash; int ret; - + + if (!S_ISDIR(dir->mode)) + return -EINVAL; + ret = proc_alloc_inum(&dp->low_ino); if (ret) return ret; @@ -309,16 +341,17 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp spin_lock(&proc_subdir_lock); - for (tmp = dir->subdir; tmp; tmp = tmp->next) + name_hash = proc_pde_name_hash(dp->name, strlen(dp->name)); + for (tmp = dir->pde_hash_buckets[name_hash]; tmp; tmp = tmp->next) if (strcmp(tmp->name, dp->name) == 0) { WARN(1, "proc_dir_entry '%s/%s' already registered\n", dir->name, dp->name); break; } - dp->next = dir->subdir; + dp->next = dir->pde_hash_buckets[name_hash]; dp->parent = dir; - dir->subdir = dp; + dir->pde_hash_buckets[name_hash] = dp; spin_unlock(&proc_subdir_lock); return 0; @@ -349,6 +382,14 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent, ent = kzalloc(sizeof(struct proc_dir_entry) + qstr.len + 1, GFP_KERNEL); if (!ent) goto out; + if (S_ISDIR(mode)) { + ent->pde_hash_buckets = kzalloc(PROC_PDE_HASH_SIZE, GFP_KERNEL); + if (!ent->pde_hash_buckets) { + kfree(ent); + ent = NULL; + goto out; + } + } memcpy(ent->name, fn, qstr.len + 1); ent->namelen = qstr.len; @@ -471,6 +512,8 @@ static void free_proc_entry(struct proc_dir_entry *de) if (S_ISLNK(de->mode)) kfree(de->data); + if (S_ISDIR(de->mode)) + kfree(de->pde_hash_buckets); kfree(de); } @@ -488,7 +531,10 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent) struct proc_dir_entry **p; struct proc_dir_entry *de = NULL; const char *fn = name; - unsigned int len; + unsigned int len, name_hash; + + if (!S_ISDIR(parent->mode)) + return; spin_lock(&proc_subdir_lock); if (__xlate_proc_name(name, &parent, &fn) != 0) { @@ -497,7 +543,8 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent) } len = strlen(fn); - for (p = &parent->subdir; *p; p=&(*p)->next ) { + name_hash = proc_pde_name_hash(fn, len); + for (p = &parent->pde_hash_buckets[name_hash]; *p; p = &(*p)->next) { if (proc_match(len, fn, *p)) { de = *p; *p = de->next; @@ -516,9 +563,11 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent) if (S_ISDIR(de->mode)) parent->nlink--; de->nlink = 0; - WARN(de->subdir, "%s: removing non-empty directory " - "'%s/%s', leaking at least '%s'\n", __func__, - de->parent->name, de->name, de->subdir->name); + if (S_ISDIR(de->mode)) + WARN(de->pde_hash_buckets[name_hash], + "%s: removing non-empty directory '%s/%s', leaking at least '%s'\n", + __func__, de->parent->name, de->name, + de->pde_hash_buckets[name_hash]->name); pde_put(de); } EXPORT_SYMBOL(remove_proc_entry); @@ -528,7 +577,10 @@ int remove_proc_subtree(const char *name, struct proc_dir_entry *parent) struct proc_dir_entry **p; struct proc_dir_entry *root = NULL, *de, *next; const char *fn = name; - unsigned int len; + unsigned int len, name_hash, hash_idx; + + if (!S_ISDIR(parent->mode)) + return -EINVAL; spin_lock(&proc_subdir_lock); if (__xlate_proc_name(name, &parent, &fn) != 0) { @@ -536,8 +588,9 @@ int remove_proc_subtree(const char *name, struct proc_dir_entry *parent) return -ENOENT; } len = strlen(fn); + name_hash = proc_pde_name_hash(fn, len); - for (p = &parent->subdir; *p; p=&(*p)->next ) { + for (p = &parent->pde_hash_buckets[name_hash]; *p; p = &(*p)->next) { if (proc_match(len, fn, *p)) { root = *p; *p = root->next; @@ -551,12 +604,15 @@ int remove_proc_subtree(const char *name, struct proc_dir_entry *parent) } de = root; while (1) { - next = de->subdir; - if (next) { - de->subdir = next->next; - next->next = NULL; - de = next; - continue; + if (S_ISDIR(de->mode)) { + hash_idx = find_first_hash_bucket(de); + if (hash_idx < PROC_PDE_HASH_BUCKETS) { + next = de->pde_hash_buckets[hash_idx]; + de->pde_hash_buckets[hash_idx] = next->next; + next->next = NULL; + de = next; + continue; + } } spin_unlock(&proc_subdir_lock); diff --git a/fs/proc/internal.h b/fs/proc/internal.h index 7da13e49128a..7c32e7821453 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -18,16 +18,28 @@ struct ctl_table_header; struct mempolicy; +#define PROC_PDE_SHIFT 6 +#define PROC_PDE_HASH_BUCKETS (1 << PROC_PDE_SHIFT) +#define PROC_PDE_HASH_MASK (PROC_PDE_HASH_BUCKETS - 1) +#define PROC_PDE_HASH_SIZE (PROC_PDE_HASH_BUCKETS * \ + sizeof(struct proc_dir_entry *)) + +static inline unsigned int proc_pde_name_hash(const unsigned char *name, + const unsigned int len) +{ + return full_name_hash(name, len) & PROC_PDE_HASH_MASK; +} + /* * This is not completely implemented yet. The idea is to * create an in-memory tree (like the actual /proc filesystem * tree) of these proc_dir_entries, so that we can dynamically * add new files to /proc. * - * The "next" pointer creates a linked list of one /proc directory, - * while parent/subdir create the directory structure (every - * /proc file has a parent, but "subdir" is NULL for all - * non-directory entries). + * The "pde_hash_buckets" pointer is a hash table of linked lists for + * one /proc directory (every /proc file has a parent, but it is NULL + * for all non-directory entries). The linked lists are implemented using + * the "next" fields of the proc_dir_entry. */ struct proc_dir_entry { unsigned int low_ino; @@ -38,7 +50,7 @@ struct proc_dir_entry { loff_t size; const struct inode_operations *proc_iops; const struct file_operations *proc_fops; - struct proc_dir_entry *next, *parent, *subdir; + struct proc_dir_entry *next, *parent; void *data; atomic_t count; /* use count */ atomic_t in_use; /* number of callers into module in progress; */ @@ -46,10 +58,37 @@ struct proc_dir_entry { struct completion *pde_unload_completion; struct list_head pde_openers; /* who did ->open, but not ->release */ spinlock_t pde_unload_lock; /* proc_fops checks and pde_users bumps */ + struct proc_dir_entry **pde_hash_buckets; /* hash table for dirs */ u8 namelen; char name[]; }; +/* index for the next non-NULL bucket in the hash table */ +static inline unsigned int find_next_hash_bucket(const struct proc_dir_entry *pde, + const unsigned int start) +{ + unsigned int i; + + if (start >= PROC_PDE_HASH_BUCKETS) + return PROC_PDE_HASH_BUCKETS; + + for (i = start; + (i < PROC_PDE_HASH_BUCKETS) && (!pde->pde_hash_buckets[i]); + i++) + ; + + if (!pde->pde_hash_buckets[i]) + i = PROC_PDE_HASH_BUCKETS; + + return i; +} + +/* index for the first non-NULL bucket in the hash table */ +static inline int find_first_hash_bucket(const struct proc_dir_entry *pde) +{ + return find_next_hash_bucket(pde, 0); +} + union proc_op { int (*proc_get_link)(struct dentry *, struct path *); int (*proc_show)(struct seq_file *m, diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index 6fc308ec105c..da2e9f4533ed 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -191,6 +191,12 @@ static __net_init int proc_net_ns_init(struct net *net) netd = kzalloc(sizeof(*netd) + 4, GFP_KERNEL); if (!netd) goto out; + netd->pde_hash_buckets = kzalloc(PROC_PDE_HASH_SIZE, GFP_KERNEL); + if (!netd->pde_hash_buckets) { + kfree(netd); + netd = NULL; + goto out; + } netd->data = net; netd->mode = S_IFDIR | S_IRUGO | S_IXUGO; @@ -217,6 +223,7 @@ out: static __net_exit void proc_net_ns_exit(struct net *net) { remove_proc_entry("stat", net->proc_net); + kfree(net->proc_net->pde_hash_buckets); kfree(net->proc_net); } diff --git a/fs/proc/root.c b/fs/proc/root.c index 094e44d4a6be..bcd830465871 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -20,6 +20,7 @@ #include <linux/mount.h> #include <linux/pid_namespace.h> #include <linux/parser.h> +#include <linux/slab.h> #include "internal.h" @@ -166,6 +167,10 @@ void __init proc_root_init(void) { int err; + proc_root.pde_hash_buckets = kzalloc(PROC_PDE_HASH_SIZE, GFP_KERNEL); + if (!proc_root.pde_hash_buckets) + return; + proc_init_inodecache(); err = register_filesystem(&proc_fs_type); if (err)