On 11/13, Cyrill Gorcunov wrote:
>
> struct signalfd_ctx {
> + rwlock_t lock;
> sigset_t sigmask;
Oh, I don't think.
rwlock_t is horrible in general, and what it can buy for signalfd?
A plain spinlock would be better. Or seqlock_t.
Whatever you do, you are trying to introduce the lock which should
serialize the access to ->sigmask correctly. In this case I think
you should split this change into 2 patches. The first one should
fix the locking, imo. sys_signalfd4() should not use ->siglock at
all, and the users which take ->siglock to read ->sigmask should be
updated.
Or,
> +#ifdef CONFIG_PROC_FS
> +static int signalfd_show_fdinfo(struct seq_file *m, struct file *f)
> +{
> + struct signalfd_ctx *ctx = f->private_data;
> + sigset_t sigmask;
> +
> + read_lock(&ctx->lock);
> + sigmask = ctx->sigmask;
> + read_unlock(&ctx->lock);
Just read ctx->sigmask lockless. Do we really care if show_fdinfo()
reads the value "in between" ?
Oleg.
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