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Wed, 22 May 2019 18:57:50 +0200 (CEST) Date: Wed, 22 May 2019 18:57:37 +0200 From: Oleg Nesterov To: Christian Brauner Subject: Re: [PATCH v1 1/2] open: add close_range() Message-ID: <20190522165737.GC4915@redhat.com> References: <20190522155259.11174-1-christian@brauner.io> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190522155259.11174-1-christian@brauner.io> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Wed, 22 May 2019 16:58:18 +0000 (UTC) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, ldv@altlinux.org, dhowells@redhat.com, linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, shuah@kernel.org, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, miklos@szeredi.hu, x86@kernel.org, torvalds@linux-foundation.org, linux-mips@vger.kernel.org, linux-xtensa@linux-xtensa.org, tkjos@android.com, arnd@arndb.de, jannh@google.com, linux-m68k@lists.linux-m68k.org, viro@zeniv.linux.org.uk, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, fweimer@redhat.com, linux-parisc@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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; } ? Then close_range() can do while (fd < max_fd) fd = close_next_fd(fd, maxfd); Oleg.