[PATCH 2/3] resource: Include resource end in walk_*() interfaces

From: Bjorn Helgaas <helgaas@kernel.org>
To: Lianbo Jiang <lijiang@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>,
	linux-kernel@vger.kernel.org, kexec@lists.infradead.org,
	tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com,
	x86@kernel.org, akpm@linux-foundation.org,
	dan.j.williams@intel.com, thomas.lendacky@amd.com,
	baiyaowei@cmss.chinamobile.com, tiwai@suse.de, bp@suse.de,
	brijesh.singh@amd.com, dyoung@redhat.com, bhe@redhat.com
Subject: [PATCH 2/3] resource: Include resource end in walk_*() interfaces
Date: Mon, 24 Sep 2018 17:14:55 -0500	[thread overview]
Message-ID: <153782729511.130337.17128646882631701192.stgit@bhelgaas-glaptop.roam.corp.google.com> (raw)
In-Reply-To: <153782698067.130337.12079523922130875402.stgit@bhelgaas-glaptop.roam.corp.google.com>

From: Bjorn Helgaas <bhelgaas@google.com>

find_next_iomem_res() finds an iomem resource that covers part of a range
described by "start, end".  All callers expect that range to be inclusive,
i.e., both start and end are included, but find_next_iomem_res() doesn't
handle the end address correctly.

If it finds an iomem resource that contains exactly the end address, it
skips it, e.g., if "start, end" is [0x0-0x10000] and there happens to be an
iomem resource [mem 0x10000-0x10000] (the single byte at 0x10000), we skip
it:

  find_next_iomem_res(...)
  {
    start = 0x0;
    end = 0x10000;
    for (p = next_resource(...)) {
      # p->start = 0x10000;
      # p->end = 0x10000;
      # we *should* return this resource, but this condition is false:
      if ((p->end >= start) && (p->start < end))
        break;

Adjust find_next_iomem_res() so it allows a resource that includes the
single byte at the end of the range.  This is a corner case that we
probably don't see in practice.

Fixes: 58c1b5b07907 ("[PATCH] memory hotadd fixes: find_next_system_ram catch range fix")
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 kernel/resource.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index 30e1bc68503b..155ec873ea4d 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -319,7 +319,7 @@ int release_resource(struct resource *old)
 EXPORT_SYMBOL(release_resource);
 
 /*
- * Finds the lowest iomem resource existing within [res->start.res->end).
+ * Finds the lowest iomem resource existing within [res->start..res->end].
  * The caller must specify res->start, res->end, res->flags, and optionally
  * desc.  If found, returns 0, res is overwritten, if not found, returns -1.
  * This function walks the whole tree and not just first level children until
@@ -352,7 +352,7 @@ static int find_next_iomem_res(struct resource *res, unsigned long desc,
 			p = NULL;
 			break;
 		}
-		if ((p->end >= start) && (p->start < end))
+		if ((p->end >= start) && (p->start <= end))
 			break;
 	}
 

