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Date: Tue, 28 Nov 2023 09:21:36 -0800
From: Gleb Smirnoff <glebius@freebsd.org>
To: Mateusz Guzik <mjg@freebsd.org>
Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org,
	dev-commits-src-main@freebsd.org
Subject: Re: git: e1e847374bcc - main - Add DEBUG_POISON_POINTER
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  Mateusz,

On Tue, Nov 28, 2023 at 04:35:40PM +0000, Mateusz Guzik wrote:
M>     Add DEBUG_POISON_POINTER
M>     
M>     If you have a pointer which you know points to stale data, you can
M>     fill it with junk so that dereference later will trap
M>     
M>     Reviewed by:    kib
M>     Sponsored by:   Rubicon Communications, LLC ("Netgate")
M>     Differential Revision:  https://reviews.freebsd.org/D40946
M> ---
M>  sys/kern/vfs_bio.c |  6 ++++++
M>  sys/sys/kassert.h  | 31 +++++++++++++++++++++++++++++++
M>  2 files changed, 37 insertions(+)
M> 
M> diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
M> index 31059f1c0a94..4e0832475c3e 100644
M> --- a/sys/kern/vfs_bio.c
M> +++ b/sys/kern/vfs_bio.c
M> @@ -159,6 +159,9 @@ nbufp(unsigned i)
M>  }
M>  
M>  caddr_t __read_mostly unmapped_buf;
M> +#ifdef INVARIANTS
M> +caddr_t	poisoned_buf = (void *)-1;
M> +#endif

Is there any good reason to use caddr_t here instead of void *?

Later it is casted back to normal void* in #define DEBUG_POISON_POINTER(x).

-- 
Gleb Smirnoff