From 35bd8c07db2ce8fd2834ef866240613a4ef982e7 Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Mon, 1 Jun 2020 12:58:26 +0300 Subject: devres: keep both device name and resource name in pretty name Sometimes debugging a device is easiest using devmem on its register map, and that can be seen with /proc/iomem. But some device drivers have many memory regions. Take for example a networking switch. Its memory map used to look like this in /proc/iomem: 1fc000000-1fc3fffff : pcie@1f0000000 1fc000000-1fc3fffff : 0000:00:00.5 1fc010000-1fc01ffff : sys 1fc030000-1fc03ffff : rew 1fc060000-1fc0603ff : s2 1fc070000-1fc0701ff : devcpu_gcb 1fc080000-1fc0800ff : qs 1fc090000-1fc0900cb : ptp 1fc100000-1fc10ffff : port0 1fc110000-1fc11ffff : port1 1fc120000-1fc12ffff : port2 1fc130000-1fc13ffff : port3 1fc140000-1fc14ffff : port4 1fc150000-1fc15ffff : port5 1fc200000-1fc21ffff : qsys 1fc280000-1fc28ffff : ana But after the patch in Fixes: was applied, the information is now presented in a much more opaque way: 1fc000000-1fc3fffff : pcie@1f0000000 1fc000000-1fc3fffff : 0000:00:00.5 1fc010000-1fc01ffff : 0000:00:00.5 1fc030000-1fc03ffff : 0000:00:00.5 1fc060000-1fc0603ff : 0000:00:00.5 1fc070000-1fc0701ff : 0000:00:00.5 1fc080000-1fc0800ff : 0000:00:00.5 1fc090000-1fc0900cb : 0000:00:00.5 1fc100000-1fc10ffff : 0000:00:00.5 1fc110000-1fc11ffff : 0000:00:00.5 1fc120000-1fc12ffff : 0000:00:00.5 1fc130000-1fc13ffff : 0000:00:00.5 1fc140000-1fc14ffff : 0000:00:00.5 1fc150000-1fc15ffff : 0000:00:00.5 1fc200000-1fc21ffff : 0000:00:00.5 1fc280000-1fc28ffff : 0000:00:00.5 That patch made a fair comment that /proc/iomem might be confusing when it shows resources without an associated device, but we can do better than just hide the resource name altogether. Namely, we can print the device name _and_ the resource name. Like this: 1fc000000-1fc3fffff : pcie@1f0000000 1fc000000-1fc3fffff : 0000:00:00.5 1fc010000-1fc01ffff : 0000:00:00.5 sys 1fc030000-1fc03ffff : 0000:00:00.5 rew 1fc060000-1fc0603ff : 0000:00:00.5 s2 1fc070000-1fc0701ff : 0000:00:00.5 devcpu_gcb 1fc080000-1fc0800ff : 0000:00:00.5 qs 1fc090000-1fc0900cb : 0000:00:00.5 ptp 1fc100000-1fc10ffff : 0000:00:00.5 port0 1fc110000-1fc11ffff : 0000:00:00.5 port1 1fc120000-1fc12ffff : 0000:00:00.5 port2 1fc130000-1fc13ffff : 0000:00:00.5 port3 1fc140000-1fc14ffff : 0000:00:00.5 port4 1fc150000-1fc15ffff : 0000:00:00.5 port5 1fc200000-1fc21ffff : 0000:00:00.5 qsys 1fc280000-1fc28ffff : 0000:00:00.5 ana Fixes: 8d84b18f5678 ("devres: always use dev_name() in devm_ioremap_resource()") Signed-off-by: Vladimir Oltean Link: https://lore.kernel.org/r/20200601095826.1757621-1-olteanv@gmail.com Signed-off-by: Greg Kroah-Hartman --- lib/devres.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'lib/devres.c') diff --git a/lib/devres.c b/lib/devres.c index 6ef51f159c54..ca0d28727cce 100644 --- a/lib/devres.c +++ b/lib/devres.c @@ -119,6 +119,7 @@ __devm_ioremap_resource(struct device *dev, const struct resource *res, { resource_size_t size; void __iomem *dest_ptr; + char *pretty_name; BUG_ON(!dev); @@ -129,7 +130,15 @@ __devm_ioremap_resource(struct device *dev, const struct resource *res, size = resource_size(res); - if (!devm_request_mem_region(dev, res->start, size, dev_name(dev))) { + if (res->name) + pretty_name = devm_kasprintf(dev, GFP_KERNEL, "%s %s", + dev_name(dev), res->name); + else + pretty_name = devm_kstrdup(dev, dev_name(dev), GFP_KERNEL); + if (!pretty_name) + return IOMEM_ERR_PTR(-ENOMEM); + + if (!devm_request_mem_region(dev, res->start, size, pretty_name)) { dev_err(dev, "can't request region for resource %pR\n", res); return IOMEM_ERR_PTR(-EBUSY); } -- cgit v1.2.3 From 7ae731a8441d70e5fb6144422a675bf1b2d6ace9 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Tue, 9 Jun 2020 13:46:42 +0300 Subject: lib: devres: add a comment about the devm_of_iomap() function We recently introduced a bug when we tried to convert of_iomap() to devm_of_iomap(). The problem was that there were two drivers mapping the same io region. The first driver was using of_iomap() and the second driver was using devm_of_iomap() and the kernel booted fine. When we converted the first drive to use devm_of_iomap() then the second driver failed with -EBUSY and the kernel couldn't boot. Let's add a comment to prevent this sort of mistake in the future. Signed-off-by: Dan Carpenter Acked-by: Arnd Bergmann Link: https://lore.kernel.org/r/20200609104642.GA43074@mwanda Signed-off-by: Greg Kroah-Hartman --- lib/devres.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'lib/devres.c') diff --git a/lib/devres.c b/lib/devres.c index ca0d28727cce..ebb1573d9ae3 100644 --- a/lib/devres.c +++ b/lib/devres.c @@ -213,6 +213,12 @@ void __iomem *devm_ioremap_resource_wc(struct device *dev, * base = devm_of_iomap(&pdev->dev, node, 0, NULL); * if (IS_ERR(base)) * return PTR_ERR(base); + * + * Please Note: This is not a one-to-one replacement for of_iomap() because the + * of_iomap() function does not track whether the region is already mapped. If + * two drivers try to map the same memory, the of_iomap() function will succeed + * but the the devm_of_iomap() function will return -EBUSY. + * */ void __iomem *devm_of_iomap(struct device *dev, struct device_node *node, int index, resource_size_t *size) -- cgit v1.2.3