bbb44e30d0
An AoE target can have multiple network ports used for AoE, and in the aoe driver, those are tracked by the aoetgt struct. These changes allow the aoe driver to handle network paths, or aoetgts, that are not working well, compared to the others. Paths that do not get responses despite the retransmission of AoE commands are marked as "tainted", and non-tainted paths are preferred. Meanwhile, the aoe driver attempts to "probe" the tainted path in the background by issuing reads of LBA 0 that are padded out to full (possibly jumbo-frame) size. If the probes get responses, then the path is "redeemed", and its taint is removed. This mechanism has been shown to be helpful in transparently handling and recovering from real-world network "brown outs" in ways that the earlier "shoot the help-needing target in the head" mechanism could not. Signed-off-by: Ed Cashin <ecashin@coraid.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
473 lines
9.5 KiB
C
473 lines
9.5 KiB
C
/* Copyright (c) 2012 Coraid, Inc. See COPYING for GPL terms. */
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/*
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* aoedev.c
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* AoE device utility functions; maintains device list.
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*/
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#include <linux/hdreg.h>
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#include <linux/blkdev.h>
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#include <linux/netdevice.h>
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#include <linux/delay.h>
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#include <linux/slab.h>
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#include <linux/bitmap.h>
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#include <linux/kdev_t.h>
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#include <linux/moduleparam.h>
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#include "aoe.h"
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static void dummy_timer(ulong);
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static void aoedev_freedev(struct aoedev *);
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static void freetgt(struct aoedev *d, struct aoetgt *t);
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static void skbpoolfree(struct aoedev *d);
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static int aoe_dyndevs = 1;
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module_param(aoe_dyndevs, int, 0644);
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MODULE_PARM_DESC(aoe_dyndevs, "Use dynamic minor numbers for devices.");
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static struct aoedev *devlist;
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static DEFINE_SPINLOCK(devlist_lock);
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/* Because some systems will have one, many, or no
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* - partitions,
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* - slots per shelf,
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* - or shelves,
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* we need some flexibility in the way the minor numbers
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* are allocated. So they are dynamic.
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*/
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#define N_DEVS ((1U<<MINORBITS)/AOE_PARTITIONS)
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static DEFINE_SPINLOCK(used_minors_lock);
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static DECLARE_BITMAP(used_minors, N_DEVS);
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static int
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minor_get_dyn(ulong *sysminor)
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{
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ulong flags;
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ulong n;
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int error = 0;
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spin_lock_irqsave(&used_minors_lock, flags);
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n = find_first_zero_bit(used_minors, N_DEVS);
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if (n < N_DEVS)
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set_bit(n, used_minors);
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else
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error = -1;
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spin_unlock_irqrestore(&used_minors_lock, flags);
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*sysminor = n * AOE_PARTITIONS;
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return error;
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}
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static int
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minor_get_static(ulong *sysminor, ulong aoemaj, int aoemin)
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{
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ulong flags;
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ulong n;
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int error = 0;
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enum {
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/* for backwards compatibility when !aoe_dyndevs,
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* a static number of supported slots per shelf */
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NPERSHELF = 16,
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};
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if (aoemin >= NPERSHELF) {
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pr_err("aoe: %s %d slots per shelf\n",
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"static minor device numbers support only",
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NPERSHELF);
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error = -1;
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goto out;
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}
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n = aoemaj * NPERSHELF + aoemin;
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if (n >= N_DEVS) {
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pr_err("aoe: %s with e%ld.%d\n",
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"cannot use static minor device numbers",
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aoemaj, aoemin);
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error = -1;
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goto out;
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}
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spin_lock_irqsave(&used_minors_lock, flags);
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if (test_bit(n, used_minors)) {
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pr_err("aoe: %s %lu\n",
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"existing device already has static minor number",
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n);
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error = -1;
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} else
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set_bit(n, used_minors);
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spin_unlock_irqrestore(&used_minors_lock, flags);
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*sysminor = n * AOE_PARTITIONS;
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out:
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return error;
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}
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static int
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minor_get(ulong *sysminor, ulong aoemaj, int aoemin)
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{
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if (aoe_dyndevs)
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return minor_get_dyn(sysminor);
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else
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return minor_get_static(sysminor, aoemaj, aoemin);
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}
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static void
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minor_free(ulong minor)
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{
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ulong flags;
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minor /= AOE_PARTITIONS;
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BUG_ON(minor >= N_DEVS);
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spin_lock_irqsave(&used_minors_lock, flags);
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BUG_ON(!test_bit(minor, used_minors));
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clear_bit(minor, used_minors);
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spin_unlock_irqrestore(&used_minors_lock, flags);
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}
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/*
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* Users who grab a pointer to the device with aoedev_by_aoeaddr
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* automatically get a reference count and must be responsible
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* for performing a aoedev_put. With the addition of async
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* kthread processing I'm no longer confident that we can
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* guarantee consistency in the face of device flushes.
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*
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* For the time being, we only bother to add extra references for
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* frames sitting on the iocq. When the kthreads finish processing
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* these frames, they will aoedev_put the device.
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*/
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void
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aoedev_put(struct aoedev *d)
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{
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ulong flags;
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spin_lock_irqsave(&devlist_lock, flags);
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d->ref--;
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spin_unlock_irqrestore(&devlist_lock, flags);
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}
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static void
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dummy_timer(ulong vp)
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{
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struct aoedev *d;
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d = (struct aoedev *)vp;
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if (d->flags & DEVFL_TKILL)
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return;
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d->timer.expires = jiffies + HZ;
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add_timer(&d->timer);
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}
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static void
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aoe_failip(struct aoedev *d)
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{
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struct request *rq;
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struct bio *bio;
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unsigned long n;
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aoe_failbuf(d, d->ip.buf);
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rq = d->ip.rq;
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if (rq == NULL)
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return;
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while ((bio = d->ip.nxbio)) {
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clear_bit(BIO_UPTODATE, &bio->bi_flags);
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d->ip.nxbio = bio->bi_next;
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n = (unsigned long) rq->special;
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rq->special = (void *) --n;
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}
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if ((unsigned long) rq->special == 0)
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aoe_end_request(d, rq, 0);
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}
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static void
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downdev_frame(struct list_head *pos)
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{
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struct frame *f;
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f = list_entry(pos, struct frame, head);
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list_del(pos);
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if (f->buf) {
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f->buf->nframesout--;
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aoe_failbuf(f->t->d, f->buf);
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}
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aoe_freetframe(f);
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}
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void
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aoedev_downdev(struct aoedev *d)
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{
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struct aoetgt *t, **tt, **te;
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struct list_head *head, *pos, *nx;
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struct request *rq;
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int i;
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d->flags &= ~DEVFL_UP;
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/* clean out active and to-be-retransmitted buffers */
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for (i = 0; i < NFACTIVE; i++) {
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head = &d->factive[i];
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list_for_each_safe(pos, nx, head)
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downdev_frame(pos);
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}
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head = &d->rexmitq;
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list_for_each_safe(pos, nx, head)
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downdev_frame(pos);
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/* reset window dressings */
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tt = d->targets;
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te = tt + NTARGETS;
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for (; tt < te && (t = *tt); tt++) {
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aoecmd_wreset(t);
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t->nout = 0;
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}
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/* clean out the in-process request (if any) */
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aoe_failip(d);
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/* fast fail all pending I/O */
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if (d->blkq) {
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while ((rq = blk_peek_request(d->blkq))) {
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blk_start_request(rq);
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aoe_end_request(d, rq, 1);
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}
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}
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if (d->gd)
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set_capacity(d->gd, 0);
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}
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static void
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aoedev_freedev(struct aoedev *d)
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{
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struct aoetgt **t, **e;
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cancel_work_sync(&d->work);
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if (d->gd) {
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aoedisk_rm_sysfs(d);
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del_gendisk(d->gd);
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put_disk(d->gd);
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blk_cleanup_queue(d->blkq);
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}
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t = d->targets;
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e = t + NTARGETS;
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for (; t < e && *t; t++)
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freetgt(d, *t);
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if (d->bufpool)
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mempool_destroy(d->bufpool);
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skbpoolfree(d);
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minor_free(d->sysminor);
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kfree(d);
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}
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/* return whether the user asked for this particular
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* device to be flushed
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*/
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static int
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user_req(char *s, size_t slen, struct aoedev *d)
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{
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char *p;
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size_t lim;
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if (!d->gd)
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return 0;
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p = strrchr(d->gd->disk_name, '/');
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if (!p)
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p = d->gd->disk_name;
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else
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p += 1;
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lim = sizeof(d->gd->disk_name);
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lim -= p - d->gd->disk_name;
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if (slen < lim)
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lim = slen;
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return !strncmp(s, p, lim);
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}
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int
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aoedev_flush(const char __user *str, size_t cnt)
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{
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ulong flags;
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struct aoedev *d, **dd;
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struct aoedev *rmd = NULL;
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char buf[16];
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int all = 0;
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int specified = 0; /* flush a specific device */
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if (cnt >= 3) {
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if (cnt > sizeof buf)
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cnt = sizeof buf;
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if (copy_from_user(buf, str, cnt))
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return -EFAULT;
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all = !strncmp(buf, "all", 3);
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if (!all)
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specified = 1;
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}
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spin_lock_irqsave(&devlist_lock, flags);
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dd = &devlist;
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while ((d = *dd)) {
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spin_lock(&d->lock);
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if (specified) {
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if (!user_req(buf, cnt, d))
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goto skip;
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} else if ((!all && (d->flags & DEVFL_UP))
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|| (d->flags & (DEVFL_GDALLOC|DEVFL_NEWSIZE))
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|| d->nopen
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|| d->ref)
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goto skip;
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*dd = d->next;
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aoedev_downdev(d);
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d->flags |= DEVFL_TKILL;
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spin_unlock(&d->lock);
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d->next = rmd;
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rmd = d;
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continue;
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skip:
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spin_unlock(&d->lock);
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dd = &d->next;
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}
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spin_unlock_irqrestore(&devlist_lock, flags);
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while ((d = rmd)) {
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rmd = d->next;
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del_timer_sync(&d->timer);
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aoedev_freedev(d); /* must be able to sleep */
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}
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return 0;
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}
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/* This has been confirmed to occur once with Tms=3*1000 due to the
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* driver changing link and not processing its transmit ring. The
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* problem is hard enough to solve by returning an error that I'm
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* still punting on "solving" this.
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*/
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static void
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skbfree(struct sk_buff *skb)
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{
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enum { Sms = 250, Tms = 30 * 1000};
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int i = Tms / Sms;
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if (skb == NULL)
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return;
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while (atomic_read(&skb_shinfo(skb)->dataref) != 1 && i-- > 0)
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msleep(Sms);
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if (i < 0) {
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printk(KERN_ERR
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"aoe: %s holds ref: %s\n",
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skb->dev ? skb->dev->name : "netif",
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"cannot free skb -- memory leaked.");
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return;
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}
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skb->truesize -= skb->data_len;
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skb_shinfo(skb)->nr_frags = skb->data_len = 0;
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skb_trim(skb, 0);
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dev_kfree_skb(skb);
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}
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static void
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skbpoolfree(struct aoedev *d)
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{
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struct sk_buff *skb, *tmp;
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skb_queue_walk_safe(&d->skbpool, skb, tmp)
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skbfree(skb);
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__skb_queue_head_init(&d->skbpool);
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}
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/* find it or allocate it */
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struct aoedev *
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aoedev_by_aoeaddr(ulong maj, int min, int do_alloc)
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{
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struct aoedev *d;
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int i;
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ulong flags;
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ulong sysminor = 0;
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spin_lock_irqsave(&devlist_lock, flags);
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for (d=devlist; d; d=d->next)
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if (d->aoemajor == maj && d->aoeminor == min) {
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d->ref++;
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break;
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}
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if (d || !do_alloc || minor_get(&sysminor, maj, min) < 0)
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goto out;
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d = kcalloc(1, sizeof *d, GFP_ATOMIC);
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if (!d)
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goto out;
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INIT_WORK(&d->work, aoecmd_sleepwork);
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spin_lock_init(&d->lock);
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skb_queue_head_init(&d->skbpool);
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init_timer(&d->timer);
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d->timer.data = (ulong) d;
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d->timer.function = dummy_timer;
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d->timer.expires = jiffies + HZ;
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add_timer(&d->timer);
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d->bufpool = NULL; /* defer to aoeblk_gdalloc */
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d->tgt = d->targets;
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d->ref = 1;
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for (i = 0; i < NFACTIVE; i++)
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INIT_LIST_HEAD(&d->factive[i]);
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INIT_LIST_HEAD(&d->rexmitq);
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d->sysminor = sysminor;
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d->aoemajor = maj;
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d->aoeminor = min;
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d->rttavg = RTTAVG_INIT;
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d->rttdev = RTTDEV_INIT;
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d->next = devlist;
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devlist = d;
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out:
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spin_unlock_irqrestore(&devlist_lock, flags);
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return d;
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}
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static void
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freetgt(struct aoedev *d, struct aoetgt *t)
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{
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struct frame *f;
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struct list_head *pos, *nx, *head;
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struct aoeif *ifp;
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for (ifp = t->ifs; ifp < &t->ifs[NAOEIFS]; ++ifp) {
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if (!ifp->nd)
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break;
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dev_put(ifp->nd);
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}
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head = &t->ffree;
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list_for_each_safe(pos, nx, head) {
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list_del(pos);
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f = list_entry(pos, struct frame, head);
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skbfree(f->skb);
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kfree(f);
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}
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kfree(t);
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}
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void
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aoedev_exit(void)
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{
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struct aoedev *d;
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ulong flags;
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aoe_flush_iocq();
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while ((d = devlist)) {
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devlist = d->next;
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spin_lock_irqsave(&d->lock, flags);
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aoedev_downdev(d);
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d->flags |= DEVFL_TKILL;
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spin_unlock_irqrestore(&d->lock, flags);
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del_timer_sync(&d->timer);
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aoedev_freedev(d);
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}
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}
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int __init
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aoedev_init(void)
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{
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return 0;
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}
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