lkml.org 
[lkml]   [2008]   [Apr]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH] fix file and descriptor handling in perfmon
From
Date

Please, review; if there's no objections, to Linus it goes, along with
the rest of arch/* files_struct sanitizing.

Races galore... General rule: as soon as it's in descriptor table,
it's over; another thread might have started IO on it/dup2() it
elsewhere/dup2() something *over* it/etc. fd_install() is the very
last step one should take - it's a point of no return.

Besides, the damn thing leaked on failure exits...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
arch/ia64/kernel/perfmon.c | 198 +++++++++++++++++++-------------------------
1 files changed, 86 insertions(+), 112 deletions(-)

diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c
index c8e4037..520749b 100644
--- a/arch/ia64/kernel/perfmon.c
+++ b/arch/ia64/kernel/perfmon.c
@@ -867,7 +867,7 @@ pfm_rvfree(void *mem, unsigned long size)
}

static pfm_context_t *
-pfm_context_alloc(void)
+pfm_context_alloc(int ctx_flags)
{
pfm_context_t *ctx;

@@ -878,6 +878,46 @@ pfm_context_alloc(void)
ctx = kzalloc(sizeof(pfm_context_t), GFP_KERNEL);
if (ctx) {
DPRINT(("alloc ctx @%p\n", ctx));
+
+ /*
+ * init context protection lock
+ */
+ spin_lock_init(&ctx->ctx_lock);
+
+ /*
+ * context is unloaded
+ */
+ ctx->ctx_state = PFM_CTX_UNLOADED;
+
+ /*
+ * initialization of context's flags
+ */
+ ctx->ctx_fl_block = (ctx_flags & PFM_FL_NOTIFY_BLOCK) ? 1 : 0;
+ ctx->ctx_fl_system = (ctx_flags & PFM_FL_SYSTEM_WIDE) ? 1: 0;
+ ctx->ctx_fl_no_msg = (ctx_flags & PFM_FL_OVFL_NO_MSG) ? 1: 0;
+ /*
+ * will move to set properties
+ * ctx->ctx_fl_excl_idle = (ctx_flags & PFM_FL_EXCL_IDLE) ? 1: 0;
+ */
+
+ /*
+ * init restart semaphore to locked
+ */
+ init_completion(&ctx->ctx_restart_done);
+
+ /*
+ * activation is used in SMP only
+ */
+ ctx->ctx_last_activation = PFM_INVALID_ACTIVATION;
+ SET_LAST_CPU(ctx, -1);
+
+ /*
+ * initialize notification message queue
+ */
+ ctx->ctx_msgq_head = ctx->ctx_msgq_tail = 0;
+ init_waitqueue_head(&ctx->ctx_msgq_wait);
+ init_waitqueue_head(&ctx->ctx_zombieq);
+
}
return ctx;
}
@@ -2165,28 +2205,20 @@ static struct dentry_operations pfmfs_dentry_operations = {
};


-static int
-pfm_alloc_fd(struct file **cfile)
+static struct file *pfm_alloc_file(pfm_context_t *ctx)
{
- int fd, ret = 0;
- struct file *file = NULL;
- struct inode * inode;
+ struct file *file;
+ struct inode *inode;
+ struct dentry *dentry;
char name[32];
struct qstr this;

- fd = get_unused_fd();
- if (fd < 0) return -ENFILE;
-
- ret = -ENFILE;
-
- file = get_empty_filp();
- if (!file) goto out;
-
/*
* allocate a new inode
*/
inode = new_inode(pfmfs_mnt->mnt_sb);
- if (!inode) goto out;
+ if (!inode)
+ return ERR_PTR(-ENOMEM);

DPRINT(("new inode ino=%ld @%p\n", inode->i_ino, inode));

@@ -2199,59 +2231,28 @@ pfm_alloc_fd(struct file **cfile)
this.len = strlen(name);
this.hash = inode->i_ino;

- ret = -ENOMEM;
-
/*
* allocate a new dcache entry
*/
- file->f_path.dentry = d_alloc(pfmfs_mnt->mnt_sb->s_root, &this);
- if (!file->f_path.dentry) goto out;
+ dentry = d_alloc(pfmfs_mnt->mnt_sb->s_root, &this);
+ if (!dentry) {
+ iput(inode);
+ return ERR_PTR(-ENOMEM);
+ }

- file->f_path.dentry->d_op = &pfmfs_dentry_operations;
+ dentry->d_op = &pfmfs_dentry_operations;
+ d_add(dentry, inode);

- d_add(file->f_path.dentry, inode);
- file->f_path.mnt = mntget(pfmfs_mnt);
- file->f_mapping = inode->i_mapping;
+ file = alloc_file(pfmfs_mnt, dentry, FMODE_READ, &pfm_file_ops);
+ if (!file) {
+ dput(dentry);
+ return ERR_PTR(-ENFILE);
+ }

- file->f_op = &pfm_file_ops;
- file->f_mode = FMODE_READ;
file->f_flags = O_RDONLY;
- file->f_pos = 0;
-
- /*
- * may have to delay until context is attached?
- */
- fd_install(fd, file);
-
- /*
- * the file structure we will use
- */
- *cfile = file;
-
- return fd;
-out:
- if (file) put_filp(file);
- put_unused_fd(fd);
- return ret;
-}
-
-static void
-pfm_free_fd(int fd, struct file *file)
-{
- struct files_struct *files = current->files;
- struct fdtable *fdt;
+ file->private_data = ctx;

- /*
- * there ie no fd_uninstall(), so we do it here
- */
- spin_lock(&files->file_lock);
- fdt = files_fdtable(files);
- rcu_assign_pointer(fdt->fd[fd], NULL);
- spin_unlock(&files->file_lock);
-
- if (file)
- put_filp(file);
- put_unused_fd(fd);
+ return file;
}

static int
@@ -2475,6 +2476,7 @@ pfm_setup_buffer_fmt(struct task_struct *task, struct file *filp, pfm_context_t

/* link buffer format and context */
ctx->ctx_buf_fmt = fmt;
+ ctx->ctx_fl_is_sampling = 1; /* assume record() is defined */

/*
* check if buffer format wants to use perfmon buffer allocation/mapping service
@@ -2669,78 +2671,45 @@ pfm_context_create(pfm_context_t *ctx, void *arg, int count, struct pt_regs *reg
{
pfarg_context_t *req = (pfarg_context_t *)arg;
struct file *filp;
+ struct path path;
int ctx_flags;
+ int fd;
int ret;

/* let's check the arguments first */
ret = pfarg_is_sane(current, req);
- if (ret < 0) return ret;
+ if (ret < 0)
+ return ret;

ctx_flags = req->ctx_flags;

ret = -ENOMEM;

- ctx = pfm_context_alloc();
- if (!ctx) goto error;
+ fd = get_unused_fd();
+ if (fd < 0)
+ return fd;

- ret = pfm_alloc_fd(&filp);
- if (ret < 0) goto error_file;
+ ctx = pfm_context_alloc(ctx_flags);
+ if (!ctx)
+ goto error;

- req->ctx_fd = ctx->ctx_fd = ret;
+ filp = pfm_alloc_file(ctx);
+ if (IS_ERR(filp)) {
+ ret = PTR_ERR(filp);
+ goto error_file;
+ }

- /*
- * attach context to file
- */
- filp->private_data = ctx;
+ req->ctx_fd = ctx->ctx_fd = fd;

/*
* does the user want to sample?
*/
if (pfm_uuid_cmp(req->ctx_smpl_buf_id, pfm_null_uuid)) {
ret = pfm_setup_buffer_fmt(current, filp, ctx, ctx_flags, 0, req);
- if (ret) goto buffer_error;
+ if (ret)
+ goto buffer_error;
}

- /*
- * init context protection lock
- */
- spin_lock_init(&ctx->ctx_lock);
-
- /*
- * context is unloaded
- */
- ctx->ctx_state = PFM_CTX_UNLOADED;
-
- /*
- * initialization of context's flags
- */
- ctx->ctx_fl_block = (ctx_flags & PFM_FL_NOTIFY_BLOCK) ? 1 : 0;
- ctx->ctx_fl_system = (ctx_flags & PFM_FL_SYSTEM_WIDE) ? 1: 0;
- ctx->ctx_fl_is_sampling = ctx->ctx_buf_fmt ? 1 : 0; /* assume record() is defined */
- ctx->ctx_fl_no_msg = (ctx_flags & PFM_FL_OVFL_NO_MSG) ? 1: 0;
- /*
- * will move to set properties
- * ctx->ctx_fl_excl_idle = (ctx_flags & PFM_FL_EXCL_IDLE) ? 1: 0;
- */
-
- /*
- * init restart semaphore to locked
- */
- init_completion(&ctx->ctx_restart_done);
-
- /*
- * activation is used in SMP only
- */
- ctx->ctx_last_activation = PFM_INVALID_ACTIVATION;
- SET_LAST_CPU(ctx, -1);
-
- /*
- * initialize notification message queue
- */
- ctx->ctx_msgq_head = ctx->ctx_msgq_tail = 0;
- init_waitqueue_head(&ctx->ctx_msgq_wait);
- init_waitqueue_head(&ctx->ctx_zombieq);
-
DPRINT(("ctx=%p flags=0x%x system=%d notify_block=%d excl_idle=%d no_msg=%d ctx_fd=%d \n",
ctx,
ctx_flags,
@@ -2755,10 +2724,14 @@ pfm_context_create(pfm_context_t *ctx, void *arg, int count, struct pt_regs *reg
*/
pfm_reset_pmu_state(ctx);

+ fd_install(fd, filp);
+
return 0;

buffer_error:
- pfm_free_fd(ctx->ctx_fd, filp);
+ path = filp->f_path;
+ put_filp(filp);
+ path_put(&path);

if (ctx->ctx_buf_fmt) {
pfm_buf_fmt_exit(ctx->ctx_buf_fmt, current, NULL, regs);
@@ -2767,6 +2740,7 @@ error_file:
pfm_context_free(ctx);

error:
+ put_unused_fd(fd);
return ret;
}

--
1.5.5.1



\
 
 \ /
  Last update: 2008-04-27 03:21    [W:0.081 / U:0.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site