On Fri, 07 Nov 2014 05:40:37 +0000 (GMT) Steven Stewart-Gallus <sstewartgallus00@xxxxxxxxxxxxxxx> wrote:
> This shouldn't be too controversial. I simply looked for where there
> was a tiny bit of waste in the message queue code.
>
It's probably better to do this as three or four separate patches.
> --- a/ipc/mqueue.c
> +++ b/ipc/mqueue.c
> @@ -278,16 +278,29 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
> mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
> info->attr.mq_msgsize);
>
> - spin_lock(&mq_lock);
> - if (u->mq_bytes + mq_bytes < u->mq_bytes ||
> - u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
> + {
> + bool too_many_open_files;
Well yes, that's what EMFILE means but "too_many_open_files" doesn't
make sense in this context!
> + long msgqueue_lim;
> + unsigned long u_bytes;
> +
> + msgqueue_lim = rlimit(RLIMIT_MSGQUEUE);
> +
> + spin_lock(&mq_lock);
> +
> + u_bytes = u->mq_bytes;
> + too_many_open_files = u_bytes + mq_bytes < u_bytes ||
> + u_bytes + mq_bytes > msgqueue_lim;
> + if (!too_many_open_files)
This test isn't really needed.
> + u->mq_bytes += mq_bytes;
> +
> spin_unlock(&mq_lock);
> +
> /* mqueue_evict_inode() releases info->messages */
> - ret = -EMFILE;
> - goto out_inode;
> + if (too_many_open_files) {
> + ret = -EMFILE;
> + goto out_inode;
> + }
> }
> - u->mq_bytes += mq_bytes;
> - spin_unlock(&mq_lock);
>
> /* all is ok */
> info->user = get_uid(u);
> @@ -423,44 +436,60 @@ static int mqueue_create(struct inode *dir, struct dentry
> *dentry,
> umode_t mode, bool excl)
> {
> struct inode *inode;
> - struct mq_attr *attr = dentry->d_fsdata;
> - int error;
> + struct mq_attr *attr;
> struct ipc_namespace *ipc_ns;
> + int error = 0;
> +
> + if (!capable(CAP_SYS_RESOURCE)) {
> + error = -ENOSPC;
> + goto finish;
> + }
Thatsabug. It only requires CAP_SYS_RESOURCE if we're trying with
queues_count >= queues_max.
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