| Message ID | 20240731233145.2485874-1-Frank.Li@nxp.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [1/1] linux/io.h: Add cleanup defination for iounmap() and memunmap() | expand |
On Thu, Aug 1, 2024, at 01:31, Frank Li wrote: > Add DEFINE_FREE for iounmap() and memunmap() to support scope based > cleanup. > > Signed-off-by: Frank Li <Frank.Li@nxp.com> > --- > include/linux/io.h | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/include/linux/io.h b/include/linux/io.h > index 59ec5eea696c4..7695d7973c8ff 100644 > --- a/include/linux/io.h > +++ b/include/linux/io.h > @@ -163,6 +163,9 @@ enum { > void *memremap(resource_size_t offset, size_t size, unsigned long flags); > void memunmap(void *addr); > > +DEFINE_FREE(iounmap, void __iomem *, if (!IS_ERR_OR_NULL(_T)) iounmap(_T)) > +DEFINE_FREE(memunmap, void *, if (!IS_ERR_OR_NULL(_T)) memunmap(_T)) I don't like the use of IS_ERR_OR_NULL(), which tends to indicate a problem in the interface design. In which cases do you expect to need scope based cleanup on an error pointer here? The only interfaces I see that returns an __iomem error pointer are the devm_* ones, but those have their own cleanup method. Arnd
On Thu, Aug 01, 2024 at 09:27:40AM +0200, Arnd Bergmann wrote: > On Thu, Aug 1, 2024, at 01:31, Frank Li wrote: > > Add DEFINE_FREE for iounmap() and memunmap() to support scope based > > cleanup. > > > > Signed-off-by: Frank Li <Frank.Li@nxp.com> > > --- > > include/linux/io.h | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/include/linux/io.h b/include/linux/io.h > > index 59ec5eea696c4..7695d7973c8ff 100644 > > --- a/include/linux/io.h > > +++ b/include/linux/io.h > > @@ -163,6 +163,9 @@ enum { > > void *memremap(resource_size_t offset, size_t size, unsigned long flags); > > void memunmap(void *addr); > > > > +DEFINE_FREE(iounmap, void __iomem *, if (!IS_ERR_OR_NULL(_T)) iounmap(_T)) > > +DEFINE_FREE(memunmap, void *, if (!IS_ERR_OR_NULL(_T)) memunmap(_T)) > > I don't like the use of IS_ERR_OR_NULL(), which tends > to indicate a problem in the interface design. Just !(_T) ? I just refer kfree()'s implementation. > > In which cases do you expect to need scope based cleanup > on an error pointer here? The only interfaces I see that > returns an __iomem error pointer are the devm_* ones, but > those have their own cleanup method. devm_* can help much especial in probe() function. but scope base cleanup also useful. Give a existed example: drivers/clocksource/timer-fsl-ftm.c static int __init ftm_timer_init(struct device_node *np) { ... priv->clksrc_base = of_iomap(np, 1); if (!priv->clksrc_base) { pr_err("ftm: unable to map source timer registers\n"); goto err_clksrc; } ... err_clksrc: iounmap(priv->clkevt_base); } If use scoped base cleanup it will be simple. ftm_timer_init() { base __free(ioumap) = of_iomap(np, 1); ... priv->clksrc_base = no_free_ptr(base); return 0; } drivers/clocksource/arm_arch_timer.c Some example need map and unmap in function such as: arch_timer_mem_frame_get_cntfrq() { base = ioremap(frame->cntbase, frame->size); ... iounmap(base); } of course this example is too simple. If there are many error branch between ioremap() and iounmap(), scoped based clean up make code simple. Frank > > Arnd
On Thu, Aug 1, 2024, at 17:15, Frank Li wrote: > On Thu, Aug 01, 2024 at 09:27:40AM +0200, Arnd Bergmann wrote: >> On Thu, Aug 1, 2024, at 01:31, Frank Li wrote: >> > diff --git a/include/linux/io.h b/include/linux/io.h >> > index 59ec5eea696c4..7695d7973c8ff 100644 >> > --- a/include/linux/io.h >> > +++ b/include/linux/io.h >> > @@ -163,6 +163,9 @@ enum { >> > void *memremap(resource_size_t offset, size_t size, unsigned long flags); >> > void memunmap(void *addr); >> > >> > +DEFINE_FREE(iounmap, void __iomem *, if (!IS_ERR_OR_NULL(_T)) iounmap(_T)) >> > +DEFINE_FREE(memunmap, void *, if (!IS_ERR_OR_NULL(_T)) memunmap(_T)) >> >> I don't like the use of IS_ERR_OR_NULL(), which tends >> to indicate a problem in the interface design. > > Just !(_T) ? I just refer kfree()'s implementation. Right, I think !(_T) is what we want here. I did see that kfree has the same construct you are adding here, but did not read up on how it got there. >> In which cases do you expect to need scope based cleanup >> on an error pointer here? The only interfaces I see that >> returns an __iomem error pointer are the devm_* ones, but >> those have their own cleanup method. > > > devm_* can help much especial in probe() function. but scope base cleanup > also useful. Yes, that's fine. My only point here is that you can't combine the cleanup function you added with devm_ioremap(), as that needs to be paired with either implicit cleanup or with devm_iounmap() but not plain iounmap(). Arnd
diff --git a/include/linux/io.h b/include/linux/io.h index 59ec5eea696c4..7695d7973c8ff 100644 --- a/include/linux/io.h +++ b/include/linux/io.h @@ -163,6 +163,9 @@ enum { void *memremap(resource_size_t offset, size_t size, unsigned long flags); void memunmap(void *addr); +DEFINE_FREE(iounmap, void __iomem *, if (!IS_ERR_OR_NULL(_T)) iounmap(_T)) +DEFINE_FREE(memunmap, void *, if (!IS_ERR_OR_NULL(_T)) memunmap(_T)) + /* * On x86 PAT systems we have memory tracking that keeps track of * the allowed mappings on memory ranges. This tracking works for
Add DEFINE_FREE for iounmap() and memunmap() to support scope based cleanup. Signed-off-by: Frank Li <Frank.Li@nxp.com> --- include/linux/io.h | 3 +++ 1 file changed, 3 insertions(+)