LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Christian Brauner <christian@brauner.io>
To: Oleg Nesterov <oleg@redhat.com>
Cc: viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org,
	torvalds@linux-foundation.org, fweimer@redhat.com,
	jannh@google.com, tglx@linutronix.de, arnd@arndb.de,
	shuah@kernel.org, dhowells@redhat.com, tkjos@android.com,
	ldv@altlinux.org, miklos@szeredi.hu, linux-alpha@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org,
	linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
	linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
	sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org,
	linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org,
	x86@kernel.org
Subject: Re: [PATCH v1 1/2] open: add close_range()
Date: Thu, 23 May 2019 16:14:48 +0200	[thread overview]
Message-ID: <20190523141447.34s3kc3fuwmoeq7n@brauner.io> (raw)
In-Reply-To: <20190523115118.pmscbd6kaqy37dym@brauner.io>

On Thu, May 23, 2019 at 01:51:18PM +0200, Christian Brauner wrote:
> On Wed, May 22, 2019 at 06:57:37PM +0200, Oleg Nesterov wrote:
> > On 05/22, Christian Brauner wrote:
> > >
> > > +static struct file *pick_file(struct files_struct *files, unsigned fd)
> > >  {
> > > -	struct file *file;
> > > +	struct file *file = NULL;
> > >  	struct fdtable *fdt;
> > >  
> > >  	spin_lock(&files->file_lock);
> > > @@ -632,15 +629,65 @@ int __close_fd(struct files_struct *files, unsigned fd)
> > >  		goto out_unlock;
> > >  	rcu_assign_pointer(fdt->fd[fd], NULL);
> > >  	__put_unused_fd(files, fd);
> > > -	spin_unlock(&files->file_lock);
> > > -	return filp_close(file, files);
> > >  
> > >  out_unlock:
> > >  	spin_unlock(&files->file_lock);
> > > -	return -EBADF;
> > > +	return file;
> > 
> > ...
> > 
> > > +int __close_range(struct files_struct *files, unsigned fd, unsigned max_fd)
> > > +{
> > > +	unsigned int cur_max;
> > > +
> > > +	if (fd > max_fd)
> > > +		return -EINVAL;
> > > +
> > > +	rcu_read_lock();
> > > +	cur_max = files_fdtable(files)->max_fds;
> > > +	rcu_read_unlock();
> > > +
> > > +	/* cap to last valid index into fdtable */
> > > +	if (max_fd >= cur_max)
> > > +		max_fd = cur_max - 1;
> > > +
> > > +	while (fd <= max_fd) {
> > > +		struct file *file;
> > > +
> > > +		file = pick_file(files, fd++);
> > 
> > Well, how about something like
> > 
> > 	static unsigned int find_next_opened_fd(struct fdtable *fdt, unsigned start)
> > 	{
> > 		unsigned int maxfd = fdt->max_fds;
> > 		unsigned int maxbit = maxfd / BITS_PER_LONG;
> > 		unsigned int bitbit = start / BITS_PER_LONG;
> > 
> > 		bitbit = find_next_bit(fdt->full_fds_bits, maxbit, bitbit) * BITS_PER_LONG;
> > 		if (bitbit > maxfd)
> > 			return maxfd;
> > 		if (bitbit > start)
> > 			start = bitbit;
> > 		return find_next_bit(fdt->open_fds, maxfd, start);
> > 	}
> 
> > 
> > 	unsigned close_next_fd(struct files_struct *files, unsigned start, unsigned maxfd)
> > 	{
> > 		unsigned fd;
> > 		struct file *file;
> > 		struct fdtable *fdt;
> > 	
> > 		spin_lock(&files->file_lock);
> > 		fdt = files_fdtable(files);
> > 		fd = find_next_opened_fd(fdt, start);
> > 		if (fd >= fdt->max_fds || fd > maxfd) {
> > 			fd = -1;
> > 			goto out;
> > 		}
> > 
> > 		file = fdt->fd[fd];
> > 		rcu_assign_pointer(fdt->fd[fd], NULL);
> > 		__put_unused_fd(files, fd);
> > 	out:
> > 		spin_unlock(&files->file_lock);
> > 
> > 		if (fd == -1u)
> > 			return fd;
> > 
> > 		filp_close(file, files);
> > 		return fd + 1;
> > 	}
> 
> Thanks, Oleg!
> 
> I kept it dumb and was about to reply that your solution introduces more
> code when it seemed we wanted to keep this very simple for now.
> But then I saw that find_next_opened_fd() already exists as
> find_next_fd(). So it's actually not bad compared to what I sent in v1.
> So - with some small tweaks (need to test it and all now) - how do we
> feel about?:

That's obviously not correct atm but I'll send out a tweaked version in
a bit.

Christian

  reply	other threads:[~2019-05-23 14:15 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-22 15:52 Christian Brauner
2019-05-22 15:52 ` [PATCH v1 2/2] tests: add close_range() tests Christian Brauner
2019-05-22 16:57 ` [PATCH v1 1/2] open: add close_range() Oleg Nesterov
2019-05-23 11:51   ` Christian Brauner
2019-05-23 14:14     ` Christian Brauner [this message]
2019-05-23 14:28       ` Christian Brauner
2019-05-23 16:21         ` Oleg Nesterov
2019-05-23 14:32     ` Jann Horn
2019-05-23 14:37       ` Christian Brauner
2019-05-23 16:22 ` Konstantin Khlebnikov
2019-05-23 16:29   ` David Laight
2019-05-23 16:33   ` Christian Brauner
2019-05-24  7:43     ` Arnd Bergmann
2019-05-24  9:57       ` Christian Brauner
2019-05-24 10:31   ` Christian Brauner

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190523141447.34s3kc3fuwmoeq7n@brauner.io \
    --to=christian@brauner.io \
    --cc=arnd@arndb.de \
    --cc=dhowells@redhat.com \
    --cc=fweimer@redhat.com \
    --cc=jannh@google.com \
    --cc=ldv@altlinux.org \
    --cc=linux-alpha@vger.kernel.org \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-ia64@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=linux-m68k@lists.linux-m68k.org \
    --cc=linux-mips@vger.kernel.org \
    --cc=linux-parisc@vger.kernel.org \
    --cc=linux-s390@vger.kernel.org \
    --cc=linux-sh@vger.kernel.org \
    --cc=linux-xtensa@linux-xtensa.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=miklos@szeredi.hu \
    --cc=oleg@redhat.com \
    --cc=shuah@kernel.org \
    --cc=sparclinux@vger.kernel.org \
    --cc=tglx@linutronix.de \
    --cc=tkjos@android.com \
    --cc=torvalds@linux-foundation.org \
    --cc=viro@zeniv.linux.org.uk \
    --cc=x86@kernel.org \
    --subject='Re: [PATCH v1 1/2] open: add close_range()' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).