3.16.85-rc1 review patch. If anyone has any objections, please let me know.
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From: Hannes Reinecke hare@suse.de
commit 1bc0eb0446158cc76562176b80623aa119afee5b upstream.
The 'reserved' page array is used as a short-cut for mapping data, saving us to allocate pages per request. However, the 'reserved' array is only capable of holding one request, so this patch introduces a mutex for protect 'sg_fd' against concurrent accesses.
Signed-off-by: Hannes Reinecke hare@suse.com Reviewed-by: Johannes Thumshirn jthumshirn@suse.de Tested-by: Johannes Thumshirn jthumshirn@suse.de Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
[toddpoynor@google.com: backport to 3.18-4.9, fixup for bad ioctl SG_SET_FORCE_LOW_DMA code removed in later versions and not modified by the original patch.]
Signed-off-by: Hannes Reinecke hare@suse.com Reviewed-by: Johannes Thumshirn jthumshirn@suse.de Tested-by: Johannes Thumshirn jthumshirn@suse.de Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Todd Poynor toddpoynor@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/scsi/sg.c | 47 ++++++++++++++++++++++++++--------------------- 1 file changed, 26 insertions(+), 21 deletions(-)
--- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -150,6 +150,7 @@ typedef struct sg_fd { /* holds the sta struct sg_device *parentdp; /* owning device */ wait_queue_head_t read_wait; /* queue read until command done */ rwlock_t rq_list_lock; /* protect access to list in req_arr */ + struct mutex f_mutex; /* protect against changes in this fd */ int timeout; /* defaults to SG_DEFAULT_TIMEOUT */ int timeout_user; /* defaults to SG_DEFAULT_TIMEOUT_USER */ Sg_scatter_hold reserve; /* buffer held for this file descriptor */ @@ -163,6 +164,7 @@ typedef struct sg_fd { /* holds the sta unsigned char next_cmd_len; /* 0: automatic, >0: use on next write() */ char keep_orphan; /* 0 -> drop orphan (def), 1 -> keep for read() */ char mmap_called; /* 0 -> mmap() never called on this fd */ + char res_in_use; /* 1 -> 'reserve' array in use */ struct kref f_ref; struct execute_work ew; } Sg_fd; @@ -206,7 +208,6 @@ static void sg_remove_sfp(struct kref *) static Sg_request *sg_get_rq_mark(Sg_fd * sfp, int pack_id); static Sg_request *sg_add_request(Sg_fd * sfp); static int sg_remove_request(Sg_fd * sfp, Sg_request * srp); -static int sg_res_in_use(Sg_fd * sfp); static Sg_device *sg_get_dev(int dev); static void sg_device_destroy(struct kref *kref);
@@ -652,6 +653,7 @@ sg_write(struct file *filp, const char _ } buf += SZ_SG_HEADER; __get_user(opcode, buf); + mutex_lock(&sfp->f_mutex); if (sfp->next_cmd_len > 0) { cmd_size = sfp->next_cmd_len; sfp->next_cmd_len = 0; /* reset so only this write() effected */ @@ -660,6 +662,7 @@ sg_write(struct file *filp, const char _ if ((opcode >= 0xc0) && old_hdr.twelve_byte) cmd_size = 12; } + mutex_unlock(&sfp->f_mutex); SCSI_LOG_TIMEOUT(4, printk( "sg_write: scsi opcode=0x%02x, cmd_size=%d\n", (int) opcode, cmd_size)); /* Determine buffer size. */ @@ -758,7 +761,7 @@ sg_new_write(Sg_fd *sfp, struct file *fi sg_remove_request(sfp, srp); return -EINVAL; /* either MMAP_IO or DIRECT_IO (not both) */ } - if (sg_res_in_use(sfp)) { + if (sfp->res_in_use) { sg_remove_request(sfp, srp); return -EBUSY; /* reserve buffer already being used */ } @@ -933,7 +936,7 @@ sg_ioctl(struct file *filp, unsigned int return result; if (val) { sfp->low_dma = 1; - if ((0 == sfp->low_dma) && (0 == sg_res_in_use(sfp))) { + if ((0 == sfp->low_dma) && !sfp->res_in_use) { val = (int) sfp->reserve.bufflen; sg_remove_scat(&sfp->reserve); sg_build_reserve(sfp, val); @@ -1008,12 +1011,18 @@ sg_ioctl(struct file *filp, unsigned int return -EINVAL; val = min_t(int, val, max_sectors_bytes(sdp->device->request_queue)); + mutex_lock(&sfp->f_mutex); if (val != sfp->reserve.bufflen) { - if (sg_res_in_use(sfp) || sfp->mmap_called) + if (sfp->mmap_called || + sfp->res_in_use) { + mutex_unlock(&sfp->f_mutex); return -EBUSY; + } + sg_remove_scat(&sfp->reserve); sg_build_reserve(sfp, val); } + mutex_unlock(&sfp->f_mutex); return 0; case SG_GET_RESERVED_SIZE: val = min_t(int, sfp->reserve.bufflen, @@ -1752,13 +1761,22 @@ sg_start_req(Sg_request *srp, unsigned c md = &map_data;
if (md) { - if (!sg_res_in_use(sfp) && dxfer_len <= rsv_schp->bufflen) + mutex_lock(&sfp->f_mutex); + if (dxfer_len <= rsv_schp->bufflen && + !sfp->res_in_use) { + sfp->res_in_use = 1; sg_link_reserve(sfp, srp, dxfer_len); - else { + } else if ((hp->flags & SG_FLAG_MMAP_IO) && sfp->res_in_use) { + mutex_unlock(&sfp->f_mutex); + return -EBUSY; + } else { res = sg_build_indirect(req_schp, sfp, dxfer_len); - if (res) + if (res) { + mutex_unlock(&sfp->f_mutex); return res; + } } + mutex_unlock(&sfp->f_mutex);
md->pages = req_schp->pages; md->page_order = req_schp->page_order; @@ -2155,6 +2173,7 @@ sg_add_sfp(Sg_device * sdp, int dev) rwlock_init(&sfp->rq_list_lock);
kref_init(&sfp->f_ref); + mutex_init(&sfp->f_mutex); sfp->timeout = SG_DEFAULT_TIMEOUT; sfp->timeout_user = SG_DEFAULT_TIMEOUT_USER; sfp->force_packid = SG_DEF_FORCE_PACK_ID; @@ -2229,20 +2248,6 @@ sg_remove_sfp(struct kref *kref) schedule_work(&sfp->ew.work); }
-static int -sg_res_in_use(Sg_fd * sfp) -{ - const Sg_request *srp; - unsigned long iflags; - - read_lock_irqsave(&sfp->rq_list_lock, iflags); - for (srp = sfp->headrp; srp; srp = srp->nextrp) - if (srp->res_used) - break; - read_unlock_irqrestore(&sfp->rq_list_lock, iflags); - return srp ? 1 : 0; -} - #ifdef CONFIG_SCSI_PROC_FS static int sg_idr_max_id(int id, void *p, void *data)