On 9/14/22 08:43, Rolf Eike Beer wrote:
Am Mittwoch, 14. September 2022, 08:18:19 CEST schrieb Helge Deller:
On 9/14/22 08:04, Li zeming wrote:
In the case of memory allocation failure, no alignment operation is
required.
Signed-off-by: Li zeming <zeming@xxxxxxxxxxxx>
---
drivers/parisc/iosapic.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/parisc/iosapic.c b/drivers/parisc/iosapic.c
index 3a8c98615634..33de438916d3 100644
--- a/drivers/parisc/iosapic.c
+++ b/drivers/parisc/iosapic.c
@@ -229,7 +229,9 @@ static struct irt_entry *iosapic_alloc_irt(int
num_entries)>
* 4-byte alignment on 32-bit kernels
*/
a = (unsigned long)kmalloc(sizeof(struct irt_entry) * num_entries
+ 8,
GFP_KERNEL);>
- a = (a + 7UL) & ~7UL;
+ if (a)
+ a = (a + 7UL) & ~7UL;
+
As you said, the adjustment isn't required, but it's still ok.
So I think the additional "if" isn't necessary and so I'm not
applying your patch.
Anyway, thanks for your help to try to improve the code!
I was about to say the same, but from looking at the code I don't think what
is in there is correct either. The comment seems outdated, because
__assume_kmalloc_alignment, which is __alignof__(unsigned long long). This
code is untouched for the entire git history, so maybe we can just change the
whole thing to
return kcalloc(num_entries, sizeof(struct irt_entry))
now?
Yes, your proposal is good.
Anyone want to send a patch (with a small comment that kcalloc() will return
at least the required 8-byte alignment)?
And these functions end up propagating an allocation error in this file and it
will never reach kernel/setup.c, which seems bad.
That part I don't understand.
The return value of iosapic_alloc_irt() is checked afterwards, but you probably
meant something else?
But I guess the only point where this really can go wrong if the PDC
returns an absurdly large number of entries.
Helge
