From 4237e0d3de38da640d7c977d68f5f7f1d207a631 Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Fri, 8 Feb 2008 04:18:27 -0800 Subject: proc: less LOCK operations during lookup Pseudo-code for lookup effectively is: LOCK kernel LOCK proc_subdir_lock find PDE UNLOCK proc_subdir_lock get inode LOCK proc_subdir_lock goto unlock UNLOCK proc_subdir_lock UNLOCK kernel We can get rid of LOCK/UNLOCK pair after getting inode simply by jumping to unlock_kernel() directly. Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/generic.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs/proc/generic.c') diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 6a2fe51..75cd8d7 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -406,12 +406,12 @@ struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nam spin_unlock(&proc_subdir_lock); error = -EINVAL; inode = proc_get_inode(dir->i_sb, ino, de); - spin_lock(&proc_subdir_lock); - break; + goto out_unlock; } } } spin_unlock(&proc_subdir_lock); +out_unlock: unlock_kernel(); if (inode) { -- cgit v1.1 From 76df0c25d0c34eba9fbb8a44106ed096553ba0e8 Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Fri, 8 Feb 2008 04:18:27 -0800 Subject: proc: simplify function prototypes Move code around so as to reduce the number of forward-declarations. Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/generic.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) (limited to 'fs/proc/generic.c') diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 75cd8d7..1c91eed 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -25,12 +25,6 @@ #include "internal.h" -static ssize_t proc_file_read(struct file *file, char __user *buf, - size_t nbytes, loff_t *ppos); -static ssize_t proc_file_write(struct file *file, const char __user *buffer, - size_t count, loff_t *ppos); -static loff_t proc_file_lseek(struct file *, loff_t, int); - DEFINE_SPINLOCK(proc_subdir_lock); static int proc_match(int len, const char *name, struct proc_dir_entry *de) @@ -40,12 +34,6 @@ static int proc_match(int len, const char *name, struct proc_dir_entry *de) return !memcmp(name, de->name, len); } -static const struct file_operations proc_file_operations = { - .llseek = proc_file_lseek, - .read = proc_file_read, - .write = proc_file_write, -}; - /* buffer size is one page but our output routines use some slack for overruns */ #define PROC_BLOCK_SIZE (PAGE_SIZE - 1024) @@ -233,6 +221,12 @@ proc_file_lseek(struct file *file, loff_t offset, int orig) return retval; } +static const struct file_operations proc_file_operations = { + .llseek = proc_file_lseek, + .read = proc_file_read, + .write = proc_file_write, +}; + static int proc_notify_change(struct dentry *dentry, struct iattr *iattr) { struct inode *inode = dentry->d_inode; -- cgit v1.1 From fd2cbe48883a01f710c2a639877e3b3e4eba6e59 Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Fri, 8 Feb 2008 04:18:28 -0800 Subject: proc: remove useless check on symlink removal proc symlinks always have valid ->data containing destination of symlink. No need to check it on removal -- proc_symlink() already done it. Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/generic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/proc/generic.c') diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 1c91eed..e37ea3e 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -673,7 +673,7 @@ void free_proc_entry(struct proc_dir_entry *de) release_inode_number(ino); - if (S_ISLNK(de->mode) && de->data) + if (S_ISLNK(de->mode)) kfree(de->data); kfree(de); } -- cgit v1.1 From 94413d8807a3c511a3675be4ce27a4d16d6408ee Mon Sep 17 00:00:00 2001 From: Zhang Rui Date: Fri, 8 Feb 2008 04:18:29 -0800 Subject: proc: detect duplicate names on registration Print a warning if PDE is registered with a name which already exists in target directory. Bug report and a simple fix can be found here: http://bugzilla.kernel.org/show_bug.cgi?id=8798 [\n fixlet and no undescriptive variable usage --adobriyan] [akpm@linux-foundation.org: make printk comprehensible] Signed-off-by: Zhang Rui Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/generic.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'fs/proc/generic.c') diff --git a/fs/proc/generic.c b/fs/proc/generic.c index e37ea3e..b9dd362 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -521,6 +521,7 @@ static const struct inode_operations proc_dir_inode_operations = { static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp) { unsigned int i; + struct proc_dir_entry *tmp; i = get_inode_number(); if (i == 0) @@ -544,6 +545,15 @@ 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) + if (strcmp(tmp->name, dp->name) == 0) { + printk(KERN_WARNING "proc_dir_entry '%s' already " + "registered\n", dp->name); + dump_stack(); + break; + } + dp->next = dir->subdir; dp->parent = dir; dir->subdir = dp; -- cgit v1.1 From 2d3a4e3666325a9709cc8ea2e88151394e8f20fc Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Fri, 8 Feb 2008 04:18:37 -0800 Subject: proc: fix ->open'less usage due to ->proc_fops flip Typical PDE creation code looks like: pde = create_proc_entry("foo", 0, NULL); if (pde) pde->proc_fops = &foo_proc_fops; Notice that PDE is first created, only then ->proc_fops is set up to final value. This is a problem because right after creation a) PDE is fully visible in /proc , and b) ->proc_fops are proc_file_operations which do not have ->open callback. So, it's possible to ->read without ->open (see one class of oopses below). The fix is new API called proc_create() which makes sure ->proc_fops are set up before gluing PDE to main tree. Typical new code looks like: pde = proc_create("foo", 0, NULL, &foo_proc_fops); if (!pde) return -ENOMEM; Fix most networking users for a start. In the long run, create_proc_entry() for regular files will go. BUG: unable to handle kernel NULL pointer dereference at virtual address 00000024 printing eip: c1188c1b *pdpt = 000000002929e001 *pde = 0000000000000000 Oops: 0002 [#1] PREEMPT SMP DEBUG_PAGEALLOC last sysfs file: /sys/block/sda/sda1/dev Modules linked in: foo af_packet ipv6 cpufreq_ondemand loop serio_raw psmouse k8temp hwmon sr_mod cdrom Pid: 24679, comm: cat Not tainted (2.6.24-rc3-mm1 #2) EIP: 0060:[] EFLAGS: 00210002 CPU: 0 EIP is at mutex_lock_nested+0x75/0x25d EAX: 000006fe EBX: fffffffb ECX: 00001000 EDX: e9340570 ESI: 00000020 EDI: 00200246 EBP: e9340570 ESP: e8ea1ef8 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 Process cat (pid: 24679, ti=E8EA1000 task=E9340570 task.ti=E8EA1000) Stack: 00000000 c106f7ce e8ee05b4 00000000 00000001 458003d0 f6fb6f20 fffffffb 00000000 c106f7aa 00001000 c106f7ce 08ae9000 f6db53f0 00000020 00200246 00000000 00000002 00000000 00200246 00200246 e8ee05a0 fffffffb e8ee0550 Call Trace: [] seq_read+0x24/0x28a [] seq_read+0x0/0x28a [] seq_read+0x24/0x28a [] seq_read+0x0/0x28a [] proc_reg_read+0x60/0x73 [] proc_reg_read+0x0/0x73 [] vfs_read+0x6c/0x8b [] sys_read+0x3c/0x63 [] sysenter_past_esp+0x5f/0xa5 [] destroy_inode+0x24/0x33 ======================= INFO: lockdep is turned off. Code: 75 21 68 e1 1a 19 c1 68 87 00 00 00 68 b8 e8 1f c1 68 25 73 1f c1 e8 84 06 e9 ff e8 52 b8 e7 ff 83 c4 10 9c 5f fa e8 28 89 ea ff fe 4e 04 79 0a f3 90 80 7e 04 00 7e f8 eb f0 39 76 34 74 33 EIP: [] mutex_lock_nested+0x75/0x25d SS:ESP 0068:e8ea1ef8 [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Alexey Dobriyan Cc: "Eric W. Biederman" Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/generic.c | 40 ++++++++++++++++++++++++++++++++++++---- 1 file changed, 36 insertions(+), 4 deletions(-) (limited to 'fs/proc/generic.c') diff --git a/fs/proc/generic.c b/fs/proc/generic.c index b9dd362..68971e6 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -562,7 +562,7 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp return 0; } -static struct proc_dir_entry *proc_create(struct proc_dir_entry **parent, +static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent, const char *name, mode_t mode, nlink_t nlink) @@ -605,7 +605,7 @@ struct proc_dir_entry *proc_symlink(const char *name, { struct proc_dir_entry *ent; - ent = proc_create(&parent,name, + ent = __proc_create(&parent, name, (S_IFLNK | S_IRUGO | S_IWUGO | S_IXUGO),1); if (ent) { @@ -630,7 +630,7 @@ struct proc_dir_entry *proc_mkdir_mode(const char *name, mode_t mode, { struct proc_dir_entry *ent; - ent = proc_create(&parent, name, S_IFDIR | mode, 2); + ent = __proc_create(&parent, name, S_IFDIR | mode, 2); if (ent) { if (proc_register(parent, ent) < 0) { kfree(ent); @@ -664,7 +664,7 @@ struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode, nlink = 1; } - ent = proc_create(&parent,name,mode,nlink); + ent = __proc_create(&parent, name, mode, nlink); if (ent) { if (proc_register(parent, ent) < 0) { kfree(ent); @@ -674,6 +674,38 @@ struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode, return ent; } +struct proc_dir_entry *proc_create(const char *name, mode_t mode, + struct proc_dir_entry *parent, + const struct file_operations *proc_fops) +{ + struct proc_dir_entry *pde; + nlink_t nlink; + + if (S_ISDIR(mode)) { + if ((mode & S_IALLUGO) == 0) + mode |= S_IRUGO | S_IXUGO; + nlink = 2; + } else { + if ((mode & S_IFMT) == 0) + mode |= S_IFREG; + if ((mode & S_IALLUGO) == 0) + mode |= S_IRUGO; + nlink = 1; + } + + pde = __proc_create(&parent, name, mode, nlink); + if (!pde) + goto out; + pde->proc_fops = proc_fops; + if (proc_register(parent, pde) < 0) + goto out_free; + return pde; +out_free: + kfree(pde); +out: + return NULL; +} + void free_proc_entry(struct proc_dir_entry *de) { unsigned int ino = de->low_ino; -- cgit v1.1