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From: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
To: Mark Tuttle <marklinux@tuttlelabs.com>,
Bart Van Assche <bart.vanassche@gmail.com>,
Jens Axboe <jens.axboe@oracle.com>,
FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>,
Mike Christie <michaelc@cs.wisc.edu>,
Ming Zhang <mingz@ele.uri.edu>, Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: struct page vs page_link
Date: Tue, 12 Feb 2008 20:20:46 -0800 [thread overview]
Message-ID: <1202876446.19945.18.camel@haakon2.linux-iscsi.org> (raw)
In-Reply-To: <9803672c0802101126u4dd171dai48ea3d21fa84091e@mail.gmail.com>
Hi Mark,
After Bark posted an BUG() when CONFIG_DEBUG_SG was used with
LIO-Target, I add the proper usage of sg_table_init() and sg_mark_end()
in the LIO-Target SE. Please update your case (if you are not doing it
already). Here are my new changes for those who are still updating
drivers to use the new include/linux/scatterlist.h API.
--nab
Index: include/iscsi_linux_defs.h
===================================================================
--- include/iscsi_linux_defs.h (revision 214)
+++ include/iscsi_linux_defs.h (revision 215)
@@ -49,11 +49,14 @@
* code, and use inline functions for legacy operation.
*/
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,24)
+# define SET_SG_TABLE(sg, cnt) sg_init_table((struct scatterlist *)&sg[0], cnt); \
+ sg_mark_end((struct scatterlist *)&sg[cnt - 1]);
# define GET_ADDR_SG(sg) sg_virt(sg)
# define GET_PAGE_SG(sg) sg_page(sg)
# define SET_PAGE_SG(sg, page) sg_assign_page(sg, page)
#else
#include <linux/scatterlist.h>
+#define SET_SG_TABLE(sg, cnt)
static inline void *GET_ADDR_SG(struct scatterlist *sg)
{
return(page_address(sg->page) + sg->offset);
As you can see, the pre 2.6.24 case expands to a nop.
In my case with LIO-Target and generating SC arrays going to the default
path (which is common for PSCSI, IBLOCK, FILE, and RAMDISK_MCP) where
se_mem_t list head struct page is mapped to struct page-link in the
contigious struct scatterlist arrays.
In the iscsi_target_transport.c:transport_calc_sg_num() and scatterlist
allocation for RAMDISK_DR and RAMDISK_MCP, I added the usage of
SET_SG_TABLE right after the array of struct scatterlist right after the
struct scatterlist array has been allocated and memset.
Index: target/iscsi_target_rd.c
===================================================================
--- target/iscsi_target_rd.c (revision 215)
+++ target/iscsi_target_rd.c (revision 217)
@@ -209,6 +209,8 @@
}
memset(sg, 0, sg_per_table * sizeof(struct scatterlist));
+ SET_SG_TABLE(sg, sg_per_table);
+
sg_table[i].sg_table = sg;
sg_table[i].rd_sg_count = sg_per_table;
sg_table[i].page_start_offset = page_offset;
Index: target/iscsi_target_transport.c
===================================================================
--- target/iscsi_target_transport.c (revision 215)
+++ target/iscsi_target_transport.c (revision 217)
@@ -5096,6 +5096,8 @@
}
memset(task->task_buf, 0, task->task_sg_num * sizeof(struct scatterlist));
+ SET_SG_TABLE(task->task_buf, task->task_sg_num);
+
DEBUG_SC("Successfully allocated task->task_sg_num: %u\n", task->task_sg_num);
return(task->task_sg_num);
On Sun, 2008-02-10 at 14:26 -0500, Mark Tuttle wrote:
> Thanks for that information, I analysed your code to get a better
> understanding of exactly what was going on and was able to
> successfully patch what I needed to.
>
> http://www.tuttleresearch.com/80211patch.html
>
> Much appreciated,
> Mark Tuttle
>
> On 2/9/08, Nicholas A. Bellinger <nab@linux-iscsi.org> wrote:
> > On Sat, 2008-02-09 at 01:28 -0500, Mark Tuttle wrote:
> > > Regarding:
> > > commit 18dabf473e15850c0dbc8ff13ac1e2806d542c15
> > >
> > > This actually breaks the 802.11 subsystem (http://80211.sf.net) which
> > > relies on the page struct. (ieee80211_crypt_wep.c, line 190) Can
> > > anyone suggest an alternative kernel function or method? As of 2.6.24,
> > > the 802.11 subsystem cannot compile.
> > >
> >
> > Greetings Mark,
> >
> > I have been updating the LIO-Target codebase to 2.6.24 recently, and
> > posted some information about what I ended up doing for struct
> > scatterlist->page changing to scatterlist->page_link and
> > include/linux/scatterlist.h
> >
> > http://lkml.org/lkml/2008/2/4/111
> >
> > Hope this helps,
> >
> > --nab
> >
> >
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>
prev parent reply other threads:[~2008-02-13 4:39 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-09 6:28 Mark Tuttle
2008-02-09 12:06 ` Nicholas A. Bellinger
2008-02-10 19:26 ` Mark Tuttle
2008-02-13 4:20 ` Nicholas A. Bellinger [this message]
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