From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [patch -v3 16/22] acpi: use memory_read_from_buffer Date: Wed, 4 Jun 2008 18:29:52 -0700 Message-ID: <20080604182952.c536f82f.akpm@linux-foundation.org> References: <20080604115633.116832712@gmail.com> <20080604115824.062644468@gmail.com> <1212628886.10730.2.camel@yakui_zhao.sh.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:60292 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756233AbYFEBa1 (ORCPT ); Wed, 4 Jun 2008 21:30:27 -0400 In-Reply-To: <1212628886.10730.2.camel@yakui_zhao.sh.intel.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Zhao Yakui Cc: Akinobu Mita , linux-kernel@vger.kernel.org, Len Brown , linux-acpi@vger.kernel.org On Thu, 05 Jun 2008 09:21:26 +0800 Zhao Yakui wrote: > On Wed, 2008-06-04 at 20:56 +0900, Akinobu Mita wrote: > > plain text document attachment > > (acpi-use-memory-read-from-buffer.patch) > > Signed-off-by: Akinobu Mita > > Cc: Len Brown > > Cc: linux-acpi@vger.kernel.org > > --- > > drivers/acpi/system.c | 15 ++------------- > > 1 file changed, 2 insertions(+), 13 deletions(-) > > > > Index: 2.6-git/drivers/acpi/system.c > > =================================================================== > > --- 2.6-git.orig/drivers/acpi/system.c > > +++ 2.6-git/drivers/acpi/system.c > > @@ -77,7 +77,6 @@ static ssize_t acpi_table_show(struct ko > > container_of(bin_attr, struct acpi_table_attr, attr); > > struct acpi_table_header *table_header = NULL; > > acpi_status status; > > - ssize_t ret_count = count; > > > > status = > > acpi_get_table(table_attr->name, table_attr->instance, > > @@ -85,18 +84,8 @@ static ssize_t acpi_table_show(struct ko > > if (ACPI_FAILURE(status)) > > return -ENODEV; > > > > - if (offset >= table_header->length) { > > - ret_count = 0; > > - goto end; > > - } > > - > > - if (offset + ret_count > table_header->length) > > - ret_count = table_header->length - offset; > > - > > - memcpy(buf, ((char *)table_header) + offset, ret_count); > > - > > - end: > > - return ret_count; > > + return memory_read_from_buffer(buf, count, &offset, > > + table_header, table_header->length); > > } > it seems that there is no definition of memory_read_from_buffer. > Where is the function of memory_read_from_buffer defined? Earlier in the patch series. (The "16/22" is a hint!) > Is there a bug about the current function of acpi_table_show? No, it's just a cleanup. From: Akinobu Mita This patch introduces memory_read_from_buffer(). The only difference between memory_read_from_buffer() and simple_read_from_buffer() is which address space the function copies to. simple_read_from_buffer copies to user space memory. memory_read_from_buffer copies to normal memory. Signed-off-by: Akinobu Mita Cc: Al Viro Cc: Doug Warzecha Cc: Zhang Rui Cc: Matt Domsch Cc: Abhay Salunke Cc: Greg Kroah-Hartman Cc: Markus Rechberger Cc: Kay Sievers Cc: Bob Moore Cc: Thomas Renninger Cc: Len Brown Cc: Benjamin Herrenschmidt Cc: "Antonino A. Daplas" Cc: Krzysztof Helt Cc: Geert Uytterhoeven Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: Peter Oberparleiter Cc: Michael Holzheu Cc: Brian King Cc: James E.J. Bottomley Cc: Andrew Vasquez Cc: Seokmann Ju Signed-off-by: Andrew Morton --- fs/libfs.c | 18 ++++++++++++++++++ include/linux/fs.h | 5 ++++- 2 files changed, 22 insertions(+), 1 deletion(-) diff -puN fs/libfs.c~introduce-memory_read_from_buffer fs/libfs.c --- a/fs/libfs.c~introduce-memory_read_from_buffer +++ a/fs/libfs.c @@ -528,6 +528,23 @@ ssize_t simple_read_from_buffer(void __u return count; } +ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, + const void *from, size_t available) +{ + loff_t pos = *ppos; + + if (pos < 0) + return -EINVAL; + if (pos >= available) + return 0; + if (count > available - pos) + count = available - pos; + memcpy(to, from + pos, count); + *ppos = pos + count; + + return count; +} + /* * Transaction based IO. * The file expects a single write which triggers the transaction, and then @@ -800,6 +817,7 @@ EXPORT_SYMBOL(simple_statfs); EXPORT_SYMBOL(simple_sync_file); EXPORT_SYMBOL(simple_unlink); EXPORT_SYMBOL(simple_read_from_buffer); +EXPORT_SYMBOL(memory_read_from_buffer); EXPORT_SYMBOL(simple_transaction_get); EXPORT_SYMBOL(simple_transaction_read); EXPORT_SYMBOL(simple_transaction_release); diff -puN include/linux/fs.h~introduce-memory_read_from_buffer include/linux/fs.h --- a/include/linux/fs.h~introduce-memory_read_from_buffer +++ a/include/linux/fs.h @@ -2025,7 +2025,10 @@ extern int simple_fill_super(struct supe extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, int *count); extern void simple_release_fs(struct vfsmount **mount, int *count); -extern ssize_t simple_read_from_buffer(void __user *, size_t, loff_t *, const void *, size_t); +extern ssize_t simple_read_from_buffer(void __user *to, size_t count, + loff_t *ppos, const void *from, size_t available); +extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, + const void *from, size_t available); #ifdef CONFIG_MIGRATION extern int buffer_migrate_page(struct address_space *, _