From: Vincent Whitchurch vincent.whitchurch@axis.com

[ Upstream commit ca05f33316559a04867295dd49f85aeedbfd6bfd ]

The reserved-memory overlap detection code fails to detect overlaps if either of the regions starts at address 0x0. The code explicitly checks for and ignores such regions, apparently in order to ignore dynamically allocated regions which have an address of 0x0 at this point. These dynamically allocated regions also have a size of 0x0 at this point, so fix this by removing the check and sorting the dynamically allocated regions ahead of any static regions at address 0x0.

For example, there are two overlaps in this case but they are not currently reported:

foo@0 { reg = <0x0 0x2000>; };

bar@0 { reg = <0x0 0x1000>; };

baz@1000 { reg = <0x1000 0x1000>; };

quux { size = <0x1000>; };

but they are after this patch:

OF: reserved mem: OVERLAP DETECTED! bar@0 (0x00000000--0x00001000) overlaps with foo@0 (0x00000000--0x00002000) OF: reserved mem: OVERLAP DETECTED! foo@0 (0x00000000--0x00002000) overlaps with baz@1000 (0x00001000--0x00002000)

Signed-off-by: Vincent Whitchurch vincent.whitchurch@axis.com Link: https://lore.kernel.org/r/ded6fd6b47b58741aabdcc6967f73eca6a3f311e.160327366... Signed-off-by: Rob Herring robh@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/of/of_reserved_mem.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c index 07dd81586c52b..7ccf077c72a05 100644 --- a/drivers/of/of_reserved_mem.c +++ b/drivers/of/of_reserved_mem.c @@ -218,6 +218,16 @@ static int __init __rmem_cmp(const void *a, const void *b) if (ra->base > rb->base) return 1;

+ /* + * Put the dynamic allocations (address == 0, size == 0) before static + * allocations at address 0x0 so that overlap detection works + * correctly. + */ + if (ra->size < rb->size) + return -1; + if (ra->size > rb->size) + return 1; + return 0; }

@@ -235,8 +245,7 @@ static void __init __rmem_check_for_overlap(void)

this = &reserved_mem[i]; next = &reserved_mem[i + 1]; - if (!(this->base && next->base)) - continue; + if (this->base + this->size > next->base) { phys_addr_t this_end, next_end;

From: Ming Lei ming.lei@redhat.com

[ Upstream commit 831e3405c2a344018a18fcc2665acc5a38c3a707 ]

The current scanning mechanism is supposed to fall back to a synchronous host scan if an asynchronous scan is in progress. However, this rule isn't strictly respected, scsi_prep_async_scan() doesn't hold scan_mutex when checking shost->async_scan. When scsi_scan_host() is called concurrently, two async scans on same host can be started and a hang in do_scan_async() is observed.

Fixes this issue by checking & setting shost->async_scan atomically with shost->scan_mutex.

Link: https://lore.kernel.org/r/20201010032539.426615-1-ming.lei@redhat.com Cc: Christoph Hellwig hch@lst.de Cc: Ewan D. Milne emilne@redhat.com Cc: Hannes Reinecke hare@suse.de Cc: Bart Van Assche bvanassche@acm.org Reviewed-by: Lee Duncan lduncan@suse.com Reviewed-by: Bart Van Assche bvanassche@acm.org Signed-off-by: Ming Lei ming.lei@redhat.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/scsi_scan.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index 3e2288af56bc3..647a057a9b6cc 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -1710,15 +1710,16 @@ static void scsi_sysfs_add_devices(struct Scsi_Host *shost) */ static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost) { - struct async_scan_data *data; + struct async_scan_data *data = NULL; unsigned long flags;

if (strncmp(scsi_scan_type, "sync", 4) == 0) return NULL;

+ mutex_lock(&shost->scan_mutex); if (shost->async_scan) { shost_printk(KERN_DEBUG, shost, "%s called twice\n", __func__); - return NULL; + goto err; }

data = kmalloc(sizeof(*data), GFP_KERNEL); @@ -1729,7 +1730,6 @@ static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost) goto err; init_completion(&data->prev_finished);

- mutex_lock(&shost->scan_mutex); spin_lock_irqsave(shost->host_lock, flags); shost->async_scan = 1; spin_unlock_irqrestore(shost->host_lock, flags); @@ -1744,6 +1744,7 @@ static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost) return data;

err: + mutex_unlock(&shost->scan_mutex); kfree(data); return NULL; }