Re: [PATCH v2 0/9] misc: Replace alloca() by g_malloc()

[Warner Losh <imp@bsdimp.com>]

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On Thu, May 6, 2021 at 7:39 AM Philippe Mathieu-Daudé <philmd@redhat.com>
wrote:

> The ALLOCA(3) man-page mentions its "use is discouraged".
> Replace few calls by equivalent GLib malloc().
>

Except g_alloc and g_malloc are not at all the same, and you can't drop in
replace one with the other.

g_alloc allocates stack space on the calling frame that's automatically
freed when the function returns.
g_malloc allocates space from the heap, and calls to it must be matched
with calls to g_free().

These patches don't do the latter, as far as I can tell, and so introduce
memory leaks unless there's something I've missed.

Warner



> Last call site is linux-user/.
>
> Since v1:
> - Converted more uses (alsaaudio, tpm, pca9552)
> - Reworked gdbstub (Alex)
> - Simplified PPC/KVM (Greg)
>
> Philippe Mathieu-Daudé (9):
>   audio/alsaaudio: Replace ALSA alloca() by malloc() equivalent
>   backends/tpm: Replace qemu_mutex_lock calls with QEMU_LOCK_GUARD
>   backends/tpm: Replace g_alloca() by g_malloc()
>   bsd-user/syscall: Replace alloca() by g_new()
>   gdbstub: Constify GdbCmdParseEntry
>   gdbstub: Only call cmd_parse_params() with non-NULL command schema
>   gdbstub: Replace alloca() + memset(0) by g_new0()
>   hw/misc/pca9552: Replace g_newa() by g_new()
>   target/ppc/kvm: Replace alloca() by g_malloc()
>
>  audio/alsaaudio.c           | 11 +++++++----
>  backends/tpm/tpm_emulator.c | 35 +++++++++++++++--------------------
>  bsd-user/syscall.c          |  3 +--
>  gdbstub.c                   | 34 +++++++++++++++-------------------
>  hw/misc/pca9552.c           |  2 +-
>  target/ppc/kvm.c            |  3 +--
>  6 files changed, 40 insertions(+), 48 deletions(-)
>
> --
> 2.26.3
>
>
>
>

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