* [PATCH] dma-debug: fix debugfs initialization order
@ 2021-07-22 9:18 ` Anthony Iliopoulos
0 siblings, 0 replies; 8+ messages in thread
From: Anthony Iliopoulos via iommu @ 2021-07-22 9:18 UTC (permalink / raw)
To: Christoph Hellwig, Marek Szyprowski, Robin Murphy; +Cc: iommu, linux-kernel
Due to link order, dma_debug_init is called before debugfs has a chance
to initialize (via debugfs_init which also happens in the core initcall
stage), so the directories for dma-debug are never created.
Move the dma_debug_init initcall from core to postcore stage so that
debugfs will already be initialized by the time this is called, making
it oblivious to link-ordering.
Fixes: 15b28bbcd567 ("dma-debug: move initialization to common code")
Signed-off-by: Anthony Iliopoulos <ailiop@suse.com>
---
kernel/dma/debug.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index 14de1271463f..49d80ef7f995 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -915,7 +915,7 @@ static int dma_debug_init(void)
pr_info("debugging enabled by kernel config\n");
return 0;
}
-core_initcall(dma_debug_init);
+postcore_initcall(dma_debug_init);
static __init int dma_debug_cmdline(char *str)
{
--
2.32.0
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH] dma-debug: fix debugfs initialization order @ 2021-07-22 9:18 ` Anthony Iliopoulos 0 siblings, 0 replies; 8+ messages in thread From: Anthony Iliopoulos @ 2021-07-22 9:18 UTC (permalink / raw) To: Christoph Hellwig, Marek Szyprowski, Robin Murphy; +Cc: iommu, linux-kernel Due to link order, dma_debug_init is called before debugfs has a chance to initialize (via debugfs_init which also happens in the core initcall stage), so the directories for dma-debug are never created. Move the dma_debug_init initcall from core to postcore stage so that debugfs will already be initialized by the time this is called, making it oblivious to link-ordering. Fixes: 15b28bbcd567 ("dma-debug: move initialization to common code") Signed-off-by: Anthony Iliopoulos <ailiop@suse.com> --- kernel/dma/debug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c index 14de1271463f..49d80ef7f995 100644 --- a/kernel/dma/debug.c +++ b/kernel/dma/debug.c @@ -915,7 +915,7 @@ static int dma_debug_init(void) pr_info("debugging enabled by kernel config\n"); return 0; } -core_initcall(dma_debug_init); +postcore_initcall(dma_debug_init); static __init int dma_debug_cmdline(char *str) { -- 2.32.0 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH] dma-debug: fix debugfs initialization order 2021-07-22 9:18 ` Anthony Iliopoulos @ 2021-07-22 10:10 ` Robin Murphy -1 siblings, 0 replies; 8+ messages in thread From: Robin Murphy @ 2021-07-22 10:10 UTC (permalink / raw) To: Anthony Iliopoulos, Christoph Hellwig, Marek Szyprowski Cc: iommu, linux-kernel On 2021-07-22 10:18, Anthony Iliopoulos wrote: > Due to link order, dma_debug_init is called before debugfs has a chance > to initialize (via debugfs_init which also happens in the core initcall > stage), so the directories for dma-debug are never created. > > Move the dma_debug_init initcall from core to postcore stage so that > debugfs will already be initialized by the time this is called, making > it oblivious to link-ordering. Playing initcall chicken here doesn't work so well - the later you initialise dma-debug itself, the more chance it has to miss early mappings and raise false positives later. As discussed previously[1] the better solution would be to decouple the debugfs setup so that just that part can be deferred until core_initcall_sync or later. Robin. [1] https://lore.kernel.org/linux-iommu/YIgGa6yF%2Fadg8OSN@kroah.com/ > Fixes: 15b28bbcd567 ("dma-debug: move initialization to common code") > Signed-off-by: Anthony Iliopoulos <ailiop@suse.com> > --- > kernel/dma/debug.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c > index 14de1271463f..49d80ef7f995 100644 > --- a/kernel/dma/debug.c > +++ b/kernel/dma/debug.c > @@ -915,7 +915,7 @@ static int dma_debug_init(void) > pr_info("debugging enabled by kernel config\n"); > return 0; > } > -core_initcall(dma_debug_init); > +postcore_initcall(dma_debug_init); > > static __init int dma_debug_cmdline(char *str) > { > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] dma-debug: fix debugfs initialization order @ 2021-07-22 10:10 ` Robin Murphy 0 siblings, 0 replies; 8+ messages in thread From: Robin Murphy @ 2021-07-22 10:10 UTC (permalink / raw) To: Anthony Iliopoulos, Christoph Hellwig, Marek Szyprowski Cc: iommu, linux-kernel On 2021-07-22 10:18, Anthony Iliopoulos wrote: > Due to link order, dma_debug_init is called before debugfs has a chance > to initialize (via debugfs_init which also happens in the core initcall > stage), so the directories for dma-debug are never created. > > Move the dma_debug_init initcall from core to postcore stage so that > debugfs will already be initialized by the time this is called, making > it oblivious to link-ordering. Playing initcall chicken here doesn't work so well - the later you initialise dma-debug itself, the more chance it has to miss early mappings and raise false positives later. As discussed previously[1] the better solution would be to decouple the debugfs setup so that just that part can be deferred until core_initcall_sync or later. Robin. [1] https://lore.kernel.org/linux-iommu/YIgGa6yF%2Fadg8OSN@kroah.com/ > Fixes: 15b28bbcd567 ("dma-debug: move initialization to common code") > Signed-off-by: Anthony Iliopoulos <ailiop@suse.com> > --- > kernel/dma/debug.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c > index 14de1271463f..49d80ef7f995 100644 > --- a/kernel/dma/debug.c > +++ b/kernel/dma/debug.c > @@ -915,7 +915,7 @@ static int dma_debug_init(void) > pr_info("debugging enabled by kernel config\n"); > return 0; > } > -core_initcall(dma_debug_init); > +postcore_initcall(dma_debug_init); > > static __init int dma_debug_cmdline(char *str) > { > ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] dma-debug: fix debugfs initialization order 2021-07-22 10:10 ` Robin Murphy @ 2021-07-22 14:10 ` Anthony Iliopoulos -1 siblings, 0 replies; 8+ messages in thread From: Anthony Iliopoulos via iommu @ 2021-07-22 14:10 UTC (permalink / raw) To: Robin Murphy; +Cc: linux-kernel, iommu, Christoph Hellwig On Thu, Jul 22, 2021 at 11:10:24AM +0100, Robin Murphy wrote: > On 2021-07-22 10:18, Anthony Iliopoulos wrote: > > Due to link order, dma_debug_init is called before debugfs has a chance > > to initialize (via debugfs_init which also happens in the core initcall > > stage), so the directories for dma-debug are never created. > > > > Move the dma_debug_init initcall from core to postcore stage so that > > debugfs will already be initialized by the time this is called, making > > it oblivious to link-ordering. > > Playing initcall chicken here doesn't work so well - the later you > initialise dma-debug itself, the more chance it has to miss early mappings > and raise false positives later. As discussed previously[1] the better > solution would be to decouple the debugfs setup so that just that part can > be deferred until core_initcall_sync or later. Thanks for pointing it out, makes sense. What about the following: From: Anthony Iliopoulos <ailiop@suse.com> Due to link order, dma_debug_init is called before debugfs has a chance to initialize (via debugfs_init which also happens in the core initcall stage), so the directories for dma-debug are never created. Decouple dma_debug_fs_init from dma_debug_init and defer its init until core_initcall_sync (after debugfs has been initialized) while letting dma-debug initialization occur as soon as possible to catch any early mappings, as suggested in [1]. [1] https://lore.kernel.org/linux-iommu/YIgGa6yF%2Fadg8OSN@kroah.com/ Fixes: 15b28bbcd567 ("dma-debug: move initialization to common code") Signed-off-by: Anthony Iliopoulos <ailiop@suse.com> --- kernel/dma/debug.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c index 14de1271463f..445754529917 100644 --- a/kernel/dma/debug.c +++ b/kernel/dma/debug.c @@ -794,7 +794,7 @@ static int dump_show(struct seq_file *seq, void *v) } DEFINE_SHOW_ATTRIBUTE(dump); -static void dma_debug_fs_init(void) +static int __init dma_debug_fs_init(void) { struct dentry *dentry = debugfs_create_dir("dma-api", NULL); @@ -807,7 +807,10 @@ static void dma_debug_fs_init(void) debugfs_create_u32("nr_total_entries", 0444, dentry, &nr_total_entries); debugfs_create_file("driver_filter", 0644, dentry, NULL, &filter_fops); debugfs_create_file("dump", 0444, dentry, NULL, &dump_fops); + + return 0; } +core_initcall_sync(dma_debug_fs_init); static int device_dma_allocations(struct device *dev, struct dma_debug_entry **out_entry) { @@ -892,8 +895,6 @@ static int dma_debug_init(void) spin_lock_init(&dma_entry_hash[i].lock); } - dma_debug_fs_init(); - nr_pages = DIV_ROUND_UP(nr_prealloc_entries, DMA_DEBUG_DYNAMIC_ENTRIES); for (i = 0; i < nr_pages; ++i) dma_debug_create_entries(GFP_KERNEL); _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH] dma-debug: fix debugfs initialization order @ 2021-07-22 14:10 ` Anthony Iliopoulos 0 siblings, 0 replies; 8+ messages in thread From: Anthony Iliopoulos @ 2021-07-22 14:10 UTC (permalink / raw) To: Robin Murphy; +Cc: Christoph Hellwig, Marek Szyprowski, iommu, linux-kernel On Thu, Jul 22, 2021 at 11:10:24AM +0100, Robin Murphy wrote: > On 2021-07-22 10:18, Anthony Iliopoulos wrote: > > Due to link order, dma_debug_init is called before debugfs has a chance > > to initialize (via debugfs_init which also happens in the core initcall > > stage), so the directories for dma-debug are never created. > > > > Move the dma_debug_init initcall from core to postcore stage so that > > debugfs will already be initialized by the time this is called, making > > it oblivious to link-ordering. > > Playing initcall chicken here doesn't work so well - the later you > initialise dma-debug itself, the more chance it has to miss early mappings > and raise false positives later. As discussed previously[1] the better > solution would be to decouple the debugfs setup so that just that part can > be deferred until core_initcall_sync or later. Thanks for pointing it out, makes sense. What about the following: From: Anthony Iliopoulos <ailiop@suse.com> Due to link order, dma_debug_init is called before debugfs has a chance to initialize (via debugfs_init which also happens in the core initcall stage), so the directories for dma-debug are never created. Decouple dma_debug_fs_init from dma_debug_init and defer its init until core_initcall_sync (after debugfs has been initialized) while letting dma-debug initialization occur as soon as possible to catch any early mappings, as suggested in [1]. [1] https://lore.kernel.org/linux-iommu/YIgGa6yF%2Fadg8OSN@kroah.com/ Fixes: 15b28bbcd567 ("dma-debug: move initialization to common code") Signed-off-by: Anthony Iliopoulos <ailiop@suse.com> --- kernel/dma/debug.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c index 14de1271463f..445754529917 100644 --- a/kernel/dma/debug.c +++ b/kernel/dma/debug.c @@ -794,7 +794,7 @@ static int dump_show(struct seq_file *seq, void *v) } DEFINE_SHOW_ATTRIBUTE(dump); -static void dma_debug_fs_init(void) +static int __init dma_debug_fs_init(void) { struct dentry *dentry = debugfs_create_dir("dma-api", NULL); @@ -807,7 +807,10 @@ static void dma_debug_fs_init(void) debugfs_create_u32("nr_total_entries", 0444, dentry, &nr_total_entries); debugfs_create_file("driver_filter", 0644, dentry, NULL, &filter_fops); debugfs_create_file("dump", 0444, dentry, NULL, &dump_fops); + + return 0; } +core_initcall_sync(dma_debug_fs_init); static int device_dma_allocations(struct device *dev, struct dma_debug_entry **out_entry) { @@ -892,8 +895,6 @@ static int dma_debug_init(void) spin_lock_init(&dma_entry_hash[i].lock); } - dma_debug_fs_init(); - nr_pages = DIV_ROUND_UP(nr_prealloc_entries, DMA_DEBUG_DYNAMIC_ENTRIES); for (i = 0; i < nr_pages; ++i) dma_debug_create_entries(GFP_KERNEL); ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH] dma-debug: fix debugfs initialization order 2021-07-22 14:10 ` Anthony Iliopoulos @ 2021-08-09 15:15 ` Christoph Hellwig -1 siblings, 0 replies; 8+ messages in thread From: Christoph Hellwig @ 2021-08-09 15:15 UTC (permalink / raw) To: Anthony Iliopoulos; +Cc: linux-kernel, iommu, Robin Murphy, Christoph Hellwig Thanks, applied. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] dma-debug: fix debugfs initialization order @ 2021-08-09 15:15 ` Christoph Hellwig 0 siblings, 0 replies; 8+ messages in thread From: Christoph Hellwig @ 2021-08-09 15:15 UTC (permalink / raw) To: Anthony Iliopoulos Cc: Robin Murphy, Christoph Hellwig, Marek Szyprowski, iommu, linux-kernel Thanks, applied. ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2021-08-09 15:15 UTC | newest] Thread overview: 8+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2021-07-22 9:18 [PATCH] dma-debug: fix debugfs initialization order Anthony Iliopoulos via iommu 2021-07-22 9:18 ` Anthony Iliopoulos 2021-07-22 10:10 ` Robin Murphy 2021-07-22 10:10 ` Robin Murphy 2021-07-22 14:10 ` Anthony Iliopoulos via iommu 2021-07-22 14:10 ` Anthony Iliopoulos 2021-08-09 15:15 ` Christoph Hellwig 2021-08-09 15:15 ` Christoph Hellwig
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.