diff options
| -rw-r--r-- | fs/proc/base.c | 268 |
1 files changed, 163 insertions, 105 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 98eaeaa9fdd..2236f7d3878 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1545,8 +1545,6 @@ static struct file_operations proc_tgid_attr_operations; static struct inode_operations proc_tgid_attr_inode_operations; #endif -static int get_tid_list(int index, unsigned int *tids, struct inode *dir); - /* SMP-safe */ static struct dentry *proc_pident_lookup(struct inode *dir, struct dentry *dentry, @@ -2029,88 +2027,83 @@ out: } #define PROC_NUMBUF 10 -#define PROC_MAXPIDS 20 /* - * Get a few tgid's to return for filldir - we need to hold the - * tasklist lock while doing this, and we must release it before - * we actually do the filldir itself, so we use a temp buffer.. + * Find the first tgid to return to user space. + * + * Usually this is just whatever follows &init_task, but if the users + * buffer was too small to hold the full list or there was a seek into + * the middle of the directory we have more work to do. + * + * In the case of a short read we start with find_task_by_pid. + * + * In the case of a seek we start with &init_task and walk nr + * threads past it. */ -static int get_tgid_list(int index, unsigned long version, unsigned int *tgids) +static struct task_struct *first_tgid(int tgid, int nr) { - struct task_struct *p; - int nr_tgids = 0; - - index--; + struct task_struct *pos = NULL; read_lock(&tasklist_lock); - p = NULL; - if (version) { - p = find_task_by_pid(version); - if (p && !thread_group_leader(p)) - p = NULL; + if (tgid && nr) { + pos = find_task_by_pid(tgid); + if (pos && !thread_group_leader(pos)) + pos = NULL; + if (pos) + nr = 0; } + /* If nr exceeds the number of processes get out quickly */ + if (nr && nr >= nr_processes()) + goto done; - if (p) - index = 0; - else - p = next_task(&init_task); + /* If we haven't found our starting place yet start with + * the init_task and walk nr tasks forward. + */ + if (!pos && (nr >= 0)) + pos = next_task(&init_task); - for ( ; p != &init_task; p = next_task(p)) { - int tgid = p->pid; - if (!pid_alive(p)) - continue; - if (--index >= 0) + for (; pos && pid_alive(pos); pos = next_task(pos)) { + if (--nr > 0) continue; - tgids[nr_tgids] = tgid; - nr_tgids++; - if (nr_tgids >= PROC_MAXPIDS) - break; + get_task_struct(pos); + goto done; } + pos = NULL; +done: read_unlock(&tasklist_lock); - return nr_tgids; + return pos; } /* - * Get a few tid's to return for filldir - we need to hold the - * tasklist lock while doing this, and we must release it before - * we actually do the filldir itself, so we use a temp buffer.. + * Find the next task in the task list. + * Return NULL if we loop or there is any error. + * + * The reference to the input task_struct is released. */ -static int get_tid_list(int index, unsigned int *tids, struct inode *dir) +static struct task_struct *next_tgid(struct task_struct *start) { - struct task_struct *leader_task = proc_task(dir); - struct task_struct *task = leader_task; - int nr_tids = 0; - - index -= 2; + struct task_struct *pos; read_lock(&tasklist_lock); - /* - * The starting point task (leader_task) might be an already - * unlinked task, which cannot be used to access the task-list - * via next_thread(). - */ - if (pid_alive(task)) do { - int tid = task->pid; - - if (--index >= 0) - continue; - if (tids != NULL) - tids[nr_tids] = tid; - nr_tids++; - if (nr_tids >= PROC_MAXPIDS) - break; - } while ((task = next_thread(task)) != leader_task); + pos = start; + if (pid_alive(start)) + pos = next_task(start); + if (pid_alive(pos) && (pos != &init_task)) { + get_task_struct(pos); + goto done; + } + pos = NULL; +done: read_unlock(&tasklist_lock); - return nr_tids; + put_task_struct(start); + return pos; } /* for the /proc/ directory itself, after non-process stuff has been done */ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir) { - unsigned int tgid_array[PROC_MAXPIDS]; char buf[PROC_NUMBUF]; unsigned int nr = filp->f_pos - FIRST_PROCESS_ENTRY; - unsigned int nr_tgids, i; - int next_tgid; + struct task_struct *task; + int tgid; if (!nr) { ino_t ino = fake_ino(0,PROC_TGID_INO); @@ -2119,62 +2112,123 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir) filp->f_pos++; nr++; } + nr -= 1; /* f_version caches the tgid value that the last readdir call couldn't * return. lseek aka telldir automagically resets f_version to 0. */ - next_tgid = filp->f_version; + tgid = filp->f_version; filp->f_version = 0; - for (;;) { - nr_tgids = get_tgid_list(nr, next_tgid, tgid_array); - if (!nr_tgids) { - /* no more entries ! */ + for (task = first_tgid(tgid, nr); + task; + task = next_tgid(task), filp->f_pos++) { + int len; + ino_t ino; + tgid = task->pid; + len = snprintf(buf, sizeof(buf), "%d", tgid); + ino = fake_ino(tgid, PROC_TGID_INO); + if (filldir(dirent, buf, len, filp->f_pos, ino, DT_DIR) < 0) { + /* returning this tgid failed, save it as the first + * pid for the next readir call */ + filp->f_version = tgid; + put_task_struct(task); break; } - next_tgid = 0; + } + return 0; +} - /* do not use the last found pid, reserve it for next_tgid */ - if (nr_tgids == PROC_MAXPIDS) { - nr_tgids--; - next_tgid = tgid_array[nr_tgids]; - } +/* + * Find the first tid of a thread group to return to user space. + * + * Usually this is just the thread group leader, but if the users + * buffer was too small or there was a seek into the middle of the + * directory we have more work todo. + * + * In the case of a short read we start with find_task_by_pid. + * + * In the case of a seek we start with the leader and walk nr + * threads past it. + */ +static struct task_struct *first_tid(struct task_struct *leader, int tid, int nr) +{ + struct task_struct *pos = NULL; + read_lock(&tasklist_lock); - for (i=0;i<nr_tgids;i++) { - int tgid = tgid_array[i]; - ino_t ino = fake_ino(tgid,PROC_TGID_INO); - unsigned long j = PROC_NUMBUF; + /* Attempt to start with the pid of a thread */ + if (tid && (nr > 0)) { + pos = find_task_by_pid(tid); + if (pos && (pos->group_leader != leader)) + pos = NULL; + if (pos) + nr = 0; + } - do - buf[--j] = '0' + (tgid % 10); - while ((tgid /= 10) != 0); + /* If nr exceeds the number of threads there is nothing todo */ + if (nr) { + int threads = 0; + task_lock(leader); + if (leader->signal) + threads = atomic_read(&leader->signal->count); + task_unlock(leader); + if (nr >= threads) + goto done; + } - if (filldir(dirent, buf+j, PROC_NUMBUF-j, filp->f_pos, ino, DT_DIR) < 0) { - /* returning this tgid failed, save it as the first - * pid for the next readir call */ - filp->f_version = tgid_array[i]; - goto out; - } - filp->f_pos++; - nr++; - } + /* If we haven't found our starting place yet start with the + * leader and walk nr threads forward. + */ + if (!pos && (nr >= 0)) + pos = leader; + + for (; pos && pid_alive(pos); pos = next_thread(pos)) { + if (--nr > 0) + continue; + get_task_struct(pos); + goto done; } -out: - return 0; + pos = NULL; +done: + read_unlock(&tasklist_lock); + return pos; +} + +/* + * Find the next thread in the thread list. + * Return NULL if there is an error or no next thread. + * + * The reference to the input task_struct is released. + */ +static struct task_struct *next_tid(struct task_struct *start) +{ + struct task_struct *pos; + read_lock(&tasklist_lock); + pos = start; + if (pid_alive(start)) + pos = next_thread(start); + if (pid_alive(pos) && (pos != start->group_leader)) + get_task_struct(pos); + else + pos = NULL; + read_unlock(&tasklist_lock); + put_task_struct(start); + return pos; } /* for the /proc/TGID/task/ directories */ static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldir) { - unsigned int tid_array[PROC_MAXPIDS]; char buf[PROC_NUMBUF]; - unsigned int nr_tids, i; struct dentry *dentry = filp->f_dentry; struct inode *inode = dentry->d_inode; + struct task_struct *leader = proc_task(inode); + struct task_struct *task; int retval = -ENOENT; ino_t ino; + int tid; unsigned long pos = filp->f_pos; /* avoiding "long long" filp->f_pos */ - if (!pid_alive(proc_task(inode))) + if (!pid_alive(leader)) goto out; retval = 0; @@ -2193,21 +2247,25 @@ static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldi /* fall through */ } - nr_tids = get_tid_list(pos, tid_array, inode); - - for (i = 0; i < nr_tids; i++) { - unsigned long j = PROC_NUMBUF; - int tid = tid_array[i]; - - ino = fake_ino(tid,PROC_TID_INO); - - do - buf[--j] = '0' + (tid % 10); - while ((tid /= 10) != 0); - - if (filldir(dirent, buf+j, PROC_NUMBUF-j, pos, ino, DT_DIR) < 0) + /* f_version caches the tgid value that the last readdir call couldn't + * return. lseek aka telldir automagically resets f_version to 0. + */ + tid = filp->f_version; + filp->f_version = 0; + for (task = first_tid(leader, tid, pos - 2); + task; + task = next_tid(task), pos++) { + int len; + tid = task->pid; + len = snprintf(buf, sizeof(buf), "%d", tid); + ino = fake_ino(tid, PROC_TID_INO); + if (filldir(dirent, buf, len, pos, ino, DT_DIR < 0)) { + /* returning this tgid failed, save it as the first + * pid for the next readir call */ + filp->f_version = tid; + put_task_struct(task); break; - pos++; + } } out: filp->f_pos = pos; |